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Python - For Loop

sequence = range(10)
for x in sequence:
    ...

Python has one of the simplest types of For Loops of any language. The 'in' operator can be used to easily iterate over any sequence type.

Java - For Loop

for ( int x = 0; x < 10; x++ ) {
    ...
}

Java uses the traditional For Loop syntax which involves defining an iteration variable, looping condition, and increment.

Javascript - For Loop

for ( var x = 0; x < 10; x++ ) {
    ...
}

Javascript uses the traditional For Loop syntax which involves defining an iteration variable, looping condition, and increment.

C - For Loop

for ( int x = 0; x < 10; x++ ) {
    ...
}

C uses the traditional For Loop syntax which involves defining an iteration variable, looping condition, and increment.

PHP - For Loop

for ( $x = 0; $x < 10; $x++ ) {
    ...
}

PHP uses the traditional For Loop syntax which involves defining an iteration variable, looping condition, and increment.

Python - While Loop

x = 0
while (x < 10):
    ...
    x += 1

Python uses a very clean While Loop syntax. The loop continues running as long as the looping condition remains true. The looping variable can be updated in the loop.

Java - While Loop

int x = 0;
while (x < 10) {
    ...
    x++;
}

Java uses the traditional While Loop syntax. The loop continues running as long as the looping condition remains true. The looping variable can be updated in the loop.

Javascript - While Loop

var x = 0;
while (x < 10) {
    ...
    x++;
}

Javascript uses the traditional While Loop syntax. The loop continues running as long as the looping condition remains true. The looping variable can be updated in the loop.

C - While Loop

int x = 0;
while (x < 10) {
    ...
    x++;
}

C uses the traditional While Loop syntax. The loop continues running as long as the looping condition remains true. The looping variable can be updated in the loop.

PHP - While Loop

$x = 0;
while ($x < 10) {
    ...
    $x++;
}

PHP uses the traditional While Loop syntax. The loop continues running as long as the looping condition remains true. The looping variable can be updated in the loop.

Python - Variable Assignment

a = 0
b = "Hello"
c = ["C", "h", "e", "e", "s", "e"]
d = { 1: "x", 2: "y", 3: "z" }
e = True

Python variables can be assigned on the fly without declaring their types first. Integers, strings, lists, dictionaries, and booleans can all be defined using a single equals sign.

Java - Variable Assignment

int a = 0;
char b = 'b';
String c = "Hello";
String[] d = {"C", "h", "e", "e", "s", "e"};
boolean e = true;

Java variables must have their types declared before assignment. Integers, characters, strings, arrays, and booleans are shown here.

Javascript - Variable Assignment

var a = 0;
var b = "Hello";
var c = ["C", "h", "e", "e", "s", "e"];
var d = { 1: "x", 2: "y", 3: "z" };
var e = true;

Javascript variables can be assigned on the fly without declaring their types first. Integers, strings, lists, objects, and booleans can all be defined using the `var` keyword and an equals sign.

C - Variable Assignment

int a = 0;
char b = 'b';
String c = "Hello";
String[] d = {"C", "h", "e", "e", "s", "e"};
boolean e = true;

C variables must have their types declared before assignment. Integers, characters, strings, arrays, and booleans are shown here.

PHP - Variable Assignment

$a = 0;
$b = "Hello";
$c = ["C", "h", "e", "e", "s", "e"];
$d["1"] = "x"; $d["2"] = "y"; $d["3"] = "z";
$e = true;

PHP variables can be assigned on the fly without declaring their types first. Integers, strings, arrays, and booleans can all be defined using the `$` symbol and an equals sign.

Python - If ... Else

if ( x == 1 ):
    ...
elif ( x == 2 ):
    ...
else:
    ...

Python conditional statements are very simple indeed.

Java - If ... Else

if ( x == 1 ) {
    ...
} else if ( x == 2 ) {
    ...
} else {
    ...
}

Java uses the traditional syntax for conditional statements.

Javascript - If ... Else

if ( x == 1 ) {
    ...
} else if ( x == 2 ) {
    ...
} else {
    ...
}

Javascript uses the traditional syntax for conditional statements.

C - If ... Else

if ( x == 1 ) {
    ...
} else if ( x == 2 ) {
    ...
} else {
    ...
}

C uses the traditional syntax for conditional statements.

PHP - If ... Else

if ( x == 1 ) {
    ...
} elseif ( x == 2 ) {
    ...
} else {
    ...
}

PHP almost uses the traditional syntax for conditional statements, but note that the `elseif` is a single word.

Python - Function

def sum(i, j):
    return i + j

Python functions are created using the `def` statement. The return type and parameter types do not need to be specified. All indented lines under the `def` statement make up the function's scope.

Java - Function

int sum(int i, int j) {
    return i + j;
}

Java functions must declare the return type before the function name, as well as the parameter types. The function's scope is delineated by curly braces.

Javascript - Function

function sum(i, j) {
    return i + j;
}

Javascript functions are defined using the `function` statement. The return type and parameter types do not need to be specified. The function's scope is delineated by curly braces.

C - Function

int sum(int i, int j) {
    return i + j;
}

C functions must declare the return type before the function name, as well as the parameter types. The function's scope is delineated by curly braces.

PHP - Function

function sum($i, $j) {
    return $i + $j;
}

PHP functions are defined using the `function` statement. The return type and parameter types do not need to be specified. The function's scope is delineated by curly braces.

Python - Class

class Person:
    def __init__(self, name):
        self.name = name
    def greet(self):
        return "I am " + self.name

Python classes contain member attributes and methods. The `__init__` method defines the constructor. By convention, `self` is the first parameter in each method and represents the instance of the class. Getter and setter methods are not needed since attributes are not private.

Java - Class

public class Person {
    private String name;
    public Person(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }
}

Java classes contain member attributes and methods. Constructors are methods created with the same name as the class itself. Members are private by default, so public getters and setters must be defined for attribute access.

Javascript - Class

class Person {
    constructor(name) {
        this.name = name;
    }
    greet() {
        return "I am " + this.name;
    }
}

Javascript classes are relatively new additions to the language. The `constructor` keyword defines the constructor. Getter and setter methods are not needed since attributes are not private.

C - Class

Gone fishin!

C does not have classes. That's why C++ was created. The closest thing in C is the `struct`, which has it's own card.

PHP - Class

class Person {
    public function __construct($name) {
        $this->name = $name;
    }
    public function greet() {
        return $this->name;
    }
}

PHP classes contain member attributes and methods. The `__construct` method defines the constructor. Getter and setter methods are not needed since attributes are not private.

Python - Try ... Catch / Except

try:
    ...
except:
    ...
finally:
    ...

Python will try to run the code in the `try` block. If an exception occurs the code in the `except` block will run. Specific exceptions can be caught using the `except(Exception1, Exception2, ...)` syntax. The code in the `finally` block will always execute.

Java - Try ... Catch / Except

try {
    ...
} catch ( Exception e ) {
    ...
} finally {
    ...
}

Java will try to run the code in the `try` block. If a matched exception occurs the code in the `catch` block will run. The code in the `finally` block will always execute.

Javascript - Try ... Catch / Except

try {
    ...
} catch ( e ) {
    ...
} finally {
    ...
}

Javascript will try to run the code in the `try` block. If an exception occurs the code in the `catch` block will run. Exception matching must be performed in the `catch` block. The code in the `finally` block will always execute.

C - Try ... Catch / Except

Gone fishin!

C does not directly support exceptions.

PHP - Try ... Catch / Except

try {
    ...
} catch ( Exception $e ) {
    ...
} finally {
    ...
}

PHP will try to run the code in the `try` block. If an exception occurs the code in the `catch` block will run. Specific exceptions can be caught using the `catch(Exception1 | Exception2 $e)` syntax. The code in the `finally` block will always execute.

Python - Switch

Gone fishin!

Python does not have a built-in Switch statement.

Java - Switch

switch( expression ) {
    case value1:
        ...;
        break;
    case value2:
        ...;
        break;
    default:
        ...;
        break;
}

The Java Switch statement accepts any expression or variable that can assume multiple values. Depending on the values, different code can be executed corresponding to each `case` statement. The `default` case is a catchall in the event that none of the explicit cases occur.

Javascript - Switch

switch( expression ) {
    case value1:
        ...;
        break;
    case value2:
        ...;
        break;
    default:
        ...;
}

The Javascript Switch statement accepts any expression or variable that can assume multiple values. Depending on the values, different code can be executed corresponding to each `case` statement. The `default` case is a catchall in the event that none of the explicit cases occur.

C - Switch

switch( expression ) {
    case value1:
        ...;
        break;
    case value2:
        ...;
        break;
    default:
        ...;
}

The C Switch statement accepts any expression or variable that can assume multiple values. Depending on the values, different code can be executed corresponding to each `case` statement. The `default` case is a catchall in the event that none of the explicit cases occur.

PHP - Switch

switch( expression ) {
    case value1:
        ...;
        break;
    case value2:
        ...;
        break;
    default:
        ...;
}

The PHP Switch statement accepts any expression or variable that can assume multiple values. Depending on the values, different code can be executed corresponding to each `case` statement. The `default` case is a catchall in the event that none of the explicit cases occur.

Python - Import / Include

import module1
import module1 as m1
from module1 import object1
from module1 import object1 as o1
from module1 import *

Python imports are used to access external code within modules. The `from` keyword can be used to import a specific object or function from a module. The `as` keyword can be used to rename the imported module or object. An asterisk can be used to import all toplevel objects from a module.

Java - Import / Include

import library.packagename.classname;
import library.packagename.*;

Java imports are used to conveniently reference code from other packages on the classpath. Classes can be imported individually or all classes can be imported from a package using the asterisk.

Javascript - Import / Include

import {obj1, obj2} from './mod.js';
import {obj1 as o1} from './mod.js';
import * as obj from './mod.js';

Javascript imports are used to access objects exported from other modules. Objects can be renamed with the `as` keyword. All objects exported from a module can be imported using an asterisk.

C - Import / Include

#include <header.h>

The #include preprocessing directive is used in C programs to access functions or objects that live in header and user files.

PHP - Import / Include

use \library\package\module;

PHP modules can be imported and accessed with the `use` statement.

Python - Print

print('Hi')

The Python Print function prints a string to the standard output.

Java - Print

System.out.println("Hi");

The `println` function from the `System.out` library is used to print strings to standard output in Java, with a newline added to the end.

Javascript - Print

console.log('Hi');

In Javascript, the `console.log` function is used to print text to the console.

C - Print

printf("%s", "Hi");

In C, the `printf` function is used to print a formatted string to the standard output.

PHP - Print

print "Hi";
echo "Hi";

In PHP, the `print` or `echo` functions can be used to output text.

Python - Arithmetic Operators

a = 8 + 4
b = a - 7
c = a * 8
d = b / a
e = b ** a
r = e % 2

Python uses the familiar set of arithmetic operators to add, subtract, multiply, divide, exponentiate, and modulo.

Java - Arithmetic Operators

int a = 8 + 4;
int b = a - 7;
int c = b * 8;
int d = b / a;
int e = 2 ** 4;
int r = 10 % 3;

Java uses the familiar set of arithmetic operators to add, subtract, multiply, divide, exponentiate, and modulo.

Javascript - Arithmetic Operators

var a = 8 + 4;
var b = a - 7;
var c = a * 8;
var d = b / a;
var e = b ** a;
var r = e % 2;

Javascript uses the familiar set of arithmetic operators to add, subtract, multiply, divide, exponentiate, and modulo.

C - Arithmetic Operators

int a = 8 + 4;
int b = a - 7;
int c = b * 8;
int d = b / a;
int e = 2 ** 4;
int r = 10 % 3;

C uses the familiar set of arithmetic operators to add, subtract, multiply, divide, exponentiate, and modulo.

PHP - Arithmetic Operators

$a = 8 + 4;
$b = $a - 7;
$c = $b * 8;
$d = $b / $a;
$e = 2 ** 4;
$r = $e % 2;

PHP uses the familiar set of arithmetic operators to add, subtract, multiply, divide, exponentiate, and modulo.

Python - Comparison Operators

a == b
b > a
b < a
b <= a
b >= a
b <> a

Python uses the standard set of operators to test equality, greater than, less than, etc. Equality uses two equals signs `==` to distinguish it from the assignment operator `=`. To test inequality, Python uses the `<>` operator. Each conditional expression returns a boolean value, either True or False.

Java - Comparison Operators

a == b
a < b
a > b
a >= b
a <= b
a != b

Java uses the standard set of operators to test equality, greater than, less than, etc. Equality uses two equals signs `==` to distinguish it from the assignment operator `=`. To test inequality, Java uses the '!=' operator. Each conditional expression returns a boolean value.

Javascript - Comparison Operators

a == b
a === b
a < b
a > b
a >= b
a <= b
a != b
a !== b

Javascript uses the standard set of operators to test equality, greater than, less than, etc. Equality uses two equals signs `==` to distinguish it from the assignment operator `=`. To test inequality, Javascript uses the `!=` operator. Notice the `===` and `!==` operators compare value AND type.

C - Comparison Operators

a == b
a < b
a > b
a >= b
a <= b
a != b

C uses the standard set of operators to test equality, greater than, less than, etc. Equality uses two equals signs `==` to distinguish it from the assignment operator '='. To test inequality, C uses the `!=` operator. Each conditional expression returns a boolean value.

PHP - Comparison Operators

$a == $b
$a === $b
$a < $b
$a > $b
$a >= $b
$a <= $b
$a != $b
$a <> $b
$a !== $b

PHP uses the standard set of operators to test equality, greater than, less than, etc. Equality uses two equals signs `==` to distinguish it from the assignment operator `=`. To test inequality, PHP uses `!=` or `<>`. Notice the `===` and `!==` operators compare value AND type.

Python - Logical Operators

a and b
a or b
not a

Python uses english words to represent the logical operators: and, or, not.

Java - Logical Operators

a && b
a || b
!a

Java uses the respective symbols to represent the logical operators: and, or, not.

Javascript - Logical Operators

a && b
a || b
!a

Javascript uses the respective symbols to represent the logical operators: and, or, not.

C - Logical Operators

a && b
a || b
!a

C uses the respective symbols to represent the logical operators: and, or, not.

PHP - Logical Operators

a && b
a and b
a || b
a or b
!a

PHP uses the respective symbols to represent the logical operators: and, or, not.

Python - Break

while a > b:
    ...
    break

Python uses the break statement to break out of the enclosing loop.

Java - Break

for ( int x : numbers ) {
     ...
     break;
}

Java uses the break statement to break out of the enclosing loop.

Javascript - Break

for ( i = 0; i < 5; i++ ) {
    ...
    break;
}

Javascript uses the break statement to break out of the enclosing loop.

C - Break

for ( int i = 0; i < 5; i++ ) {
    ...
    break;
}

C uses the break statement to break out of the enclosing loop.

PHP - Break

for ( $i = 0; $i < 5; $i++ ) {
    ...
    break;
}

PHP uses the break statement to break out of the enclosing loop.

Python - Continue

while a > b:
    ...
    continue

Python uses the continue statement to start the next instruction at the beginning of the enclosing loop.

Java - Continue

for ( int x : numbers ) {
     ...
     continue;
}

Java uses the continue statement to start the next instruction at the beginning of the enclosing loop.

Javascript - Continue

for ( i = 0; i < 5; i++ ) {
    ...
    continue;
}

Javascript uses the continue statement to start the next instruction at the beginning of the enclosing loop.

C - Continue

for ( int i = 0; i < 5; i++ ) {
    ...
    continue;
}

C uses the continue statement to start the next instruction at the beginning of the enclosing loop.

PHP - Continue

for ( $i = 0; $i < 5; $i++ ) {
    ...
    continue;
}

PHP uses the continue statement to start the next instruction at the beginning of the enclosing loop.

Python - Comments

# This is a simple single line comment
"""The triple quote
comment can span many lines"""

Python uses two formats for comments, depending on whether they are single-line or multi-line comments.

Java - Comments

// This is a single line comment
/* This comment can span many lines */

Java uses two formats for comments, depending on whether they are single-line or multi-line comments.

Javascript - Comments

// This is a single line comment
/* This comment can span many lines */

Javascript uses two formats for comments, depending on whether they are single-line or multi-line comments.

C - Comments

/* This comment can span many lines */
// This was not originally supported by C

C was the original language to introduce this multi-line style for comments. However later versions of C started supporting the C++ style single-line comments.

PHP - Comments

# This is a single line comment
// This is also a single line comment
/* This comment can span many lines */

PHP supports shell style comments and both single and multi-line C style comments.

Python - Return

def func( ):
    ...
    return a, b

Python uses the return statement to exit from a function, optionally returning zero, one, more values.

Java - Return

class A {
    int fun( ) {
        ...
        return x;
    }
}

Java uses the return statement to exit from a function, optionally returning a value.

Javascript - Return

function fun( ) {
    ...
    return x;
}

Javascript uses the return statement to exit from a function, optionally returning a value.

C - Return

int fun( ) {
    ...
    return x;
}

C uses the return statement to exit from a function, optionally returning a value.

PHP - Return

function fun( ) {
    ...
    return $x;
}

PHP uses the return statement to exit from a function, optionally returning a value.

Python - Ternary Operator

x if ( x > 0 ) else y

Python uses a unique syntax for the ternary operator to shorten the traditional if-else clause.

Java - Ternary Operator

( x > 0 ) ? x : y;

Java uses the ternary operator as short hand for the if-else clause. If the condition evaluates to true, the value after the question mark is returned. Otherwise, the value after the colon is returned.

Javascript - Ternary Operator

( x > 0 ) ? x : y;

Javascript uses the ternary operator as short hand for the if-else clause. If the condition evaluates to true, the value after the question mark is returned. Otherwise, the value after the colon is returned.

C - Ternary Operator

( x > 0 ) ? x : y;

C uses the ternary operator as short hand for the if-else clause. If the condition evaluates to true, the value after the question mark is returned. Otherwise, the value after the colon is returned.

PHP - Ternary Operator

( $x > 0 ) ? $x : $y

PHP uses the ternary operator as short hand for the if-else clause. If the condition evaluates to true, the value after the question mark is returned. Otherwise, the value after the colon is returned.

Python - Raise / Throw

if x > 20:
    raise Exception("x must be less than 20")

Python uses the raise statement to generate an exception under user-defined conditions.

Java - Raise / Throw

if ( x > 20 ) {
    throw new Exception("x must be < 20");
}

Java uses the throw statement to generate an exception under user-defined conditions.

Javascript - Raise / Throw

if ( x > 20 ) {
    throw "x must be < 20";    
}

Javascript uses the throw statement to generate an exception under user-defined conditions.

C - Raise / Throw

Gone fishin!

C does not support exceptions, one must rely on return values or asserts to handle exceptional conditions.

PHP - Raise / Throw

if ( $x > 20 ) {
    throw new Exception("x must be > 20");
}

PHP uses the throw statement to generate an exception under user-defined conditions.

Python - Assert

assert x > b

Python uses the assert statement to terminate a program when an expression is false.

Java - Assert

assert x > 20: "x must be > 20;

Java uses the assert statement to terminate a program when an expression is false.

Javascript - Assert

assert( x > 20 );

Javascript uses the assert statement to terminate a program when an expression is false.

C - Assert

#include <assert.h>
...
void fun() {
    ...
    assert( x > 20 );
}

C uses the assert statement to terminate a program when an expression is false.

PHP - Assert

result = assert( $x > 20, "x must be > 20" );

PHP uses the assert statement to terminate a program when an expression is false. The behavior of assert is controlled by assert_options().

Python - Dates

import datetime
n = datetime.datetime.now()

Python uses the datetime module to get the current time.

Java - Dates

Date now = new Date();

Java uses the Date() class to get the current time.

Javascript - Dates

var now = Date.now();

Javascript the Date() class can be used to get the current time.

C - Dates

#include <time.h>
...
time_t now = time(NULL);

C uses the time library to get the current date and time.

PHP - Dates

$now = date("Y/m/d");

PHP uses the date function with a format string to get the current date and time.

Python - Open File

f1 = open( "f.txt", "r" )
f2 = open( "f.txt", "w" )
f3 = open( "f.txt", "a" )

Python can open a file for reading, writing, or appending, using the respective file mode as the second argument to the `open` function.

Java - Open File

import java.io.File;
...
File file = new File( "f.txt" );

Java can open a file for reading or writing.

Javascript - Open File

var f1 = fopen( "f.txt", 0 );
var f2 = fopen( "f.txt", 3 );

Javascript can open a file for reading or writing, depending on the value of the second argument to the `fopen` function. 0 is for reading, 3 is for writing.

C - Open File

#include <stdio.h>
...
FILE *f1 = fopen( "f.txt", "r" );
FILE *f2 = fopen( "f.txt", "w" );
FILE *f3 = fopen( "f.txt", "a" );

C can open a file for reading, writing, or appending, using the respective file mode as the second argument to the `open` function.

PHP - Open File

$f1 = fopen( "f.txt", "r" );
$f2 = fopen( "f.txt", "w" );

PHP can open a file for reading or writing using the respective file mode as the second argument to the `fopen` function.

Python - Read from File

f = open( "f.txt", "r" )
content = f.read()

Python can read all data from a file object that was opened in read mode using the `read()` method.

Java - Read from File

import java.io.File;
import java.util.Scanner;
...
File f = new File( "f.txt" );
Scanner s = new Scanner(f);
while ( s.hasNextLine() ) {
    String l = s.nextLine();
    System.out.println(l);
}

Java can use the scanner class to read from a file, line by line.

Javascript - Read from File

var f = fopen( "f.txt", 0 );
var content = fread( f, len );

Javascript can read the content of an open file using the `fread()` function. The second argument to `fread()` specifies the length of content to read.

C - Read from File

FILE *f = fopen( "f.txt", "r" );
char c = fgetc(f);
while ( c != EOF ) {
    printf("%c", c);
    c = fgets(f);
}

C can use the `fgetc()` function to read characters from a file one by one.

PHP - Read from File

$f = fopen( "f.txt", "r" );
$s = filesize("f.txt");
$c = fread( $f, $s );

PHP can read a file with the `fread()` function. The second argument is the filesize. The `filesize()` function can be used to get the size of the entire file.

Python - Write to File

f = open( "f.txt", "w" )
f.write( "text" )

Python can write to an open file object using the `write` method.

Java - Write to File

import java.io.FileWriter;
...
FileWriter fw = new FileWriter( "f.txt" );
fw.write( "text" );

Java can write to a file using the FileWriter object and its `write` method.

Javascript - Write to File

var f = fopen( "f.txt", 3 );
fwrite( f, "text" );

Javascript can write to an open file using the `fwrite` function.

C - Write to File

FILE *f = fopen( "f.txt", "w" );
fprintf(f, "%s", "text");

C can write to an open file using the `fprintf()` function.

PHP - Write to File

$f = fopen( "f.txt", "w" );
fwrite( $f, "text" );

PHP can write to an open file using the `fwrite()` function.

Python - Close File

f.close()

Python uses the `close()` method to close files.

Java - Close File

Gone fishin!

Java doesn't have a close function since a file opened with `new File('f.txt')` represents a path and not the file itself. Java utilities to read and write from files handle the closing process.

Javascript - Close File

fclose(f);

Javascript uses the `fclose()` function to close files.

C - Close File

fclose(f);

C uses the `fclose()` function to close files.

PHP - Close File

fclose($f);

PHP uses the `fclose()` function to close files.

Python - User Input

x = input("Type input: ")

Python uses the `input()` function prompt the user for input.

Java - User Input

import java.util.Scanner;
Scanner s = new Scanner(System.in);
System.out.println("Type input: ");
String i = s.nextLine();

Java uses a Scanner object combined with the standard input to read values from the user.

Javascript - User Input

var i = prompt("Type input: ");

Javascript uses the `prompt()` function to display a prompt dialog to the user.

C - User Input

#include <stdio.h>
...
char s[10];
printf("Type input: ");
fgets(s, 10, stdin);

C uses the `fgets()` function to accept input from an input stream. In this case we specify that `fgets` accepts 10 characters of input from the standard input.

PHP - User Input

echo "Type input: ";
$f = fopen( "php://stdin", "r" );
$line = fgets($f);

PHP uses the `fopen()` with the standard input stdin and `fgets()` to read input from a user.

Python - Anonymous / Lambda Function

lambda x : 2 * x

Python uses the lambda keyword to create anonymous functions.

Java - Anonymous / Lambda Function

(int x) -> 2 * x;

Java uses the arrow operator to map a function expression to a return value and create an anonymous function.

Javascript - Anonymous / Lambda Function

function() {
    alert("Hi");
}

Javascript creates an anonymous function any time the `function` statement is used without specifying a function name.

C - Anonymous / Lambda Function

Gone fishin!

C does not support anonymous functions.

PHP - Anonymous / Lambda Function

function() {
    echo "Hi.";
}

PHP creates an anonymous function any time the `function` statement is used without specifying a function name.

Python - Inheritance

class ChildClass( ParentClass ):
    pass

Python implements inheritance by allowing the user to specify a superclass as an argument in the subclass definition.

Java - Inheritance

class ChildClass extends ParentClass {
    ...
}

Java implements inheritance via the `extends` keyword.

Javascript - Inheritance

function ChildClass( x, y ) {
    ParentClass.call( this, x );
    this.y = y;
}
ChildClass.prototype = new ParentClass();

Javascript allows creating an inheritance model by calling the constructor of the superclass and passing any required parameters. Note the last line where we set the prototype of the subclass to a new empty instance of the superclass.

C - Inheritance

Gone fishin!

C does not support inheritance.

PHP - Inheritance

class ChildClass extends ParentClass {
    ...
}

PHP implements inheritance via the `extends` keyword.

Python - Null / None / Undefined

x = None

Python uses the `None` keyword to represent null values.

Java - Null / None / Undefined

String x = null;

Java uses the `null` keyword to represent null values.

Javascript - Null / None / Undefined

var x = null;
var y = undefined;

Javascript uses the `null` or `undefined` keyword to represent null values.

C - Null / None / Undefined

char *x = NULL;

C uses a macro to define NULL as the actual null value '\0', or the NULL byte.

PHP - Null / None / Undefined

$val = NULL;

PHP uses the `NULL` keyword to represent null values.

Python - Pass

if True:
    pass

Python uses pass to represent a placeholder statement that does nothing. The reason Python needs this statement is that brackets aren't used to identify the end of an empty scoped block.

Java - Pass

if ( true ) { }

Java uses empty brackets to represent a placeholder statement that does nothing.

Javascript - Pass

if ( true ) { }

Javascript uses empty brackets to represent a placeholder statement that does nothing.

C - Pass

if ( 1 ) { }

C uses empty brackets to represent a placeholder statement that does nothing.

PHP - Pass

if ( true ) { }

PHP uses empty brackets to represent a placeholder statement that does nothing.

Python - Advanced Assignment

a += 5
a -= 5
a *= 5
a /= 5
a %= 5

Python combines a logical operation (add, subtract, multiply, divide and modulo) with an equals sign, subsequently assigning the result of the operation to the left operand.

Java - Advanced Assignment

int a += 5;
int a -= 5;
int a *= 5;
int a /= 5;
int a %= 5;

Java combines a logical operation (add, subtract, multiply, divide and modulo) with an equals sign, subsequently assigning the result of the operation to the left operand.

Javascript - Advanced Assignment

var a += 5;
var a -= 5;
var a *= 5;
var a /= 5;
var a %= 5;

Javascript combines a logical operation (add, subtract, multiply, divide and modulo) with an equals sign, subsequently assigning the result of the operation to the left operand.

C - Advanced Assignment

int a += 5;
int a -= 5;
int a *= 5;
int a /= 5;
int a %= 5;

C combines a logical operation (add, subtract, multiply, divide and modulo) with an equals sign, subsequently assigning the result of the operation to the left operand.

PHP - Advanced Assignment

$a += 5;
$a -= 5;
$a *= 5;
$a /= 5;
$a %= 5;

PHP combines a logical operation (add, subtract, multiply, divide and modulo) with an equals sign, subsequently assigning the result of the operation to the left operand.

Python - Casting

w = 1;
x = str(w)
y = int(x)
z = float(y)

Python uses a set of type functions for casting.

Java - Casting

int w = 1;
String x = (String) w;
int y = (int) x;
float z = (float) y;

Java uses the type wrapped in parenthesis before the variable for casting.

Javascript - Casting

var w = 1;
var x = String(w);
var y = Number(x);

Javascript uses a set of type functions and built-in object methods for casting.

C - Casting

int w = 1;
long x = (long) w;
float y = (float) x;
double z = (double) y;

C uses the type wrapped in parenthesis before the variable for casting.

PHP - Casting

$w = 1;
$x = (string) w;
$y = (int) x;
$z = (float) y;

PHP uses the type wrapped in parenthesis before the variable for casting.

Python - Bitwise Operators

b = a & 0x1001
b = a | 0x1001
b = ~a
b = a ^ 0x4
b = a << 2
b = a >> 2

Python supports the respective bitwise operations: and, or, not, xor, shift right and shift left.

Java - Bitwise Operators

int b = a & 0x1001;
int b = a | 0x1001;
int b = ~a;
int b = a ^ 0x4;
int b = a << 2;
int b = a >> 2;

Java supports the respective bitwise operations: and, or, not, xor, shift right and shift left.

Javascript - Bitwise Operators

var b = a & 0x1001;
var b = a | 0x1001;
var b = ~a;
var b = a ^ 0x4;
var b = a << 2;
var b = a >> 2;

Javascript supports the respective bitwise operations: and, or, not, xor, shift right and shift left.

C - Bitwise Operators

int b = a & 0x1001;
int b = a | 0x1001;
int b = ~a;
int b = a ^ 0x4;
int b = a << 2;
int b = a >> 2;

C supports the respective bitwise operations: and, or, not, xor, shift right and shift left.

PHP - Bitwise Operators

$b = $a & 0x1001;
$b = $a | 0x1001;
$b = ~$a;
$b = $a ^ 0x4;
$b = $a << 2;
$b = $a >> 2;

PHP supports the respective bitwise operations: and, or, not, xor, shift right and shift left.

Python - Constructor

class Fake():
    def __init__(self, x):
        this.x = x

Python uses the special `__init__()` method with the conventional `self` argument to define the class constructor. `self` represents the instance of the class being referenced.

Java - Constructor

class Fake {
    public Fake(String x) {
        this.x = x;
    }
}

Java implements constructors by recognizing methods that have the same name as the class. `this` represents the instance of the class being referenced.

Javascript - Constructor

class Fake {
    constructor(x) {
       this.x = x;
    }
}

Javascript defines constructors using the `constructor()` method. `this` represents the instance of the class being referenced.

C - Constructor

Gone fishin!

C does not supports classes and therefore does not support constructors.

PHP - Constructor

class Fake {
    function __construct($x) {
       $this->x = $x;
    }
}

PHP defines constructors using the `__construct()` method. `$this` represents the instance of the class being referenced.

Python - Create Instance

f = Fake("Hi")

Python will instantiate an object from a class definition by calling it with parenthesis and the respective arguments. Arguments will be passed to the class constructor.

Java - Create Instance

Fake f = new Fake("Hi");

Java will instantiate an object from a class definition using the `new` keyword. Arguments will be passed to the class constructor.

Javascript - Create Instance

var f = new Fake("Hi");

Javascript will instantiate an object from a class definition using the `new` keyword. Arguments will be passed to the class constructor.

C - Create Instance

Gone fishin!

C does not support classes and therefore does not support instance creation.

PHP - Create Instance

$f = new Fake("Hi");

PHP will instantiate an object from a class definition using the `new` keyword. Arguments will be passed to the class constructor.

Python - List / Array Length

len(list)

The Python `len()` function returns the length of a list.

Java - List / Array Length

arr.length;

Java arrays have the `length` property which can be used to return their length.

Javascript - List / Array Length

arr.length;

Javascript arrays have the `length` property which can be used to return their length.

C - List / Array Length

sizeof(arr) / sizeof(arr[0]);

C uses the `sizeof()` function to get the size of data types including arrays. Since size returns the total size or the array, we divide it by the size of an array item to get the the length.

PHP - List / Array Length

count($array);

PHP uses the `count()` function to get the length of an array.

Python - String Length

len("string")

The Python `len()` function returns the length of a string.

Java - String Length

str.length();

The Java String class provides the `length()` method.

Javascript - String Length

str.length;

Javascript strings have the length property.

C - String Length

#include<string.h>
strlen("string");

C uses the `strlen()` function to get the length of strings.

PHP - String Length

strlen("string");

PHP uses the `strlen()` function to get the length of strings.

Python - Index List / Array

list[0]

Python uses square brackets to get a list index.

Java - Index List / Array

arr[0];

Java uses square brackets to get an array index.

Javascript - Index List / Array

arr[0];

Javascript uses square brackets to get an array index.

C - Index List / Array

arr[0];

C uses square brackets to get an array index.

PHP - Index List / Array

arr[0];

PHP uses square brackets to to get an array index.

Python - Add to List / Array

list.append(x)

Python uses the `append()` method to add elements to a list.

Java - Add to List / Array

ArrayList<String> arr = new ArrayList<String>();
arr.add(x);

The Java `ArrayList` class provides the `add()` method to append an element to an array.

Javascript - Add to List / Array

arr.push(x);

Javascript uses the `push()` method to add elements to an array.

C - Add to List / Array

arr[i] = element;

C uses direct index assignment to modify values in an array.

PHP - Add to List / Array

array_push( $arr, $newItem );
$arr[] = $newItem;

PHP provides the `array_push()` function or direct item assignment to an empty index to add elements to an array.

Python - Remove from List / Array

list.pop()

Python uses the `pop()` method to remove (and return) the last element from a list.

Java - Remove from List / Array

ArrayList<String> arr = new ArrayList<String>();
arr.remove(i);

The Java ArrayList class provides the `remove()` method to remove an array element at the specified index.

Javascript - Remove from List / Array

arr.pop();

Javascript uses the `pop()` method to remove (and return) the last element from an array.

C - Remove from List / Array

arr[i] = NULL;

C uses direct item assignment to nullify an array element.

PHP - Remove from List / Array

array_pop($arr);

PHP uses the `array_pop()` function to remove (and return) the last element from an array.

Python - Sort List / Array

l = [2, 3, 1]
l.sort()
nl = sorted(l)

Python lists are sorted in-place with the `.sort()` method. To return a new sorted list instead of sorting in-place, use the built-in `sorted()` function instead.

Java - Sort List / Array

import java.util.ArrayList;
import java.util.Collections; 
...
ArrayList<Integer> a = new ArrayList<Integer>();
a.add(2);
a.add(3);
a.add(1);
Collections.sort(a);

Java ArrayLists can be sorted in-place using the the `Collections.sort()` method.

Javascript - Sort List / Array

var a = [2, 3, 1];
a.sort();

Javascript arrays are sorted in-place with the `.sort()` method.

C - Sort List / Array

#include <stdio.h>
#include <stdlib.h>
...
int compare( const void* x, const void* y) {
    int int_x = *((int*)x);
    int int_y = *((int*)y);

    if (int_x == int_y) return 0;
    else if (int_x < int_y) return -1;
    else return 1;
}
int a[] = {2, 3, 1};
qsort( a, 3, sizeof(int), compare );

C arrays can be sorted using the `qsort()` function along with a custom defined comparison function.

PHP - Sort List / Array

$a = [2, 3, 1]; 
sort($a);

PHP arrays can be sorted in-place using the `sort()` function.

Python - Replace List / Array Item

l = [ "a", "b", "z" ]
l[2] = "c"

Python uses index assignment to replace existing list items.

Java - Replace List / Array Item

import java.util.ArrayList;
...
ArrayList<String> a = new ArrayList<String>();
a.add("a");
a.add("b");
a.add("z");
a.set(2, "c");

Java uses the `.set()` method to replace an item in an ArrayList.

Javascript - Replace List / Array Item

a = [ "a", "b", "z" ];
a[2] = "c";

Javascript uses index assignment to replace existing list items.

C - Replace List / Array Item

char a[] = {'a', 'b', 'z'};
a[2] = 'c';

C uses index assignment to replace existing list items.

PHP - Replace List / Array Item

$a = [ "a", "b", "z" ]; 
$a[2] = "c";

PHP uses index assignment to replace existing list items.

Python - Slice List / Array

l = ["a", "b", "c", "d", "e"]
b = l[0:3]

Python uses the `:` operator to get a slice of a list. The number before the colon is the index of the first element of the slice, inclusive. The number after the colon is the index of the the last item of the slice, exclusive. This example slice will return ['a', 'b', 'c'].

Java - Slice List / Array

import java.util.List;
import java.util.ArrayList;
...
List<String> a = new ArrayList<String>();
a.add("a");
a.add("b");
a.add("c");
a.add("d");
a.add("e");
List<String> b = a.subList(0, 3);

Java uses `.subList()` method to get an array slice. The first argument is the index of the first element of the slice, inclusive. The second argument is the index of the the last item of the slice, exclusive. This example slice will return ['a', 'b', 'c'].

Javascript - Slice List / Array

var a = ["a", "b", "c", "d", "e"];
b = a.slice(0, 3);

Javascript uses `.slice()` method to get an array slice. The first argument is the index of the first element of the slice, inclusive. The second argument is the index of the the last item of the slice, exclusive. This example slice will return ['a', 'b', 'c'].

C - Slice List / Array

char a[5] = {'a', 'b', 'c', 'd', 'e'};
char b[2];
memcpy(b, a, 3 * sizeof(*x));

C can effectively slice an array using the `memcpy()` function. The first argument is the array to copy the slice to. The second argument is the array to copy the slice from. The third argument is the size of the desired number of elements to slice. This example slice will return ['a', 'b', 'c'].

PHP - Slice List / Array

$a = ["a", "b", "c", "d", "e"];
$b = array_slice($a, 0, 3);

PHP uses uses `array_slice()` function to get an array slice. The first argument is the index of the first element of the slice, inclusive. The second argument is the index of the the last item of the slice, exclusive. This example slice will return ['a', 'b', 'c'].

Python - Replace Array Slice

l = ["a", "b", "c", "d", "e"]
l[0:3] = "x"

Python allows assignments to slices which will have the effect of replacing the slice. In this example the final list will be ['x', 'd', 'e']

Java - Replace Array Slice

List<String> a = new ArrayList<String>();
a.add("a");
a.add("b");
a.add("c");
a.add("d");
a.add("e");
a = a.subList(3, 5);
a.add(0, "x");

Java can use a combination of the `.sublist()` method, reassignment, and the `.add()` method to replace slices. In this example the final array will be ['x', 'd', 'e']

Javascript - Replace Array Slice

var a = ["a", "b", "c", "d", "e"];
a = ["x"].concat(a.slice(3, 5));

Javascript can use the `.concat()` method along with the `.slice()` method to redefine an array based on the desired slices. In this example the final array will be ['x', 'd', 'e']

C - Replace Array Slice

#include <stdio.h>
...
char x[5] = {'a', 'b', 'c', 'd', 'e'};
char *n = 'x';
char *nl = '';
memcpy(x, &n, sizeof(*x));
memcpy(&x[1], &x[3], 2 * sizeof(*x));
memcpy(&x[3], &nl, sizeof(*x));
memcpy(&x[4], &nl, sizeof(*x));

C can use the `memcpy()` function along with pointers to simulate slice replacement in arrays. Note that in this case we need to manually reset the 4th and 5th positions in the array to the null byte. In this example the final array will be ['x', 'd', 'e']

PHP - Replace Array Slice

$a = ["a", "b", "c", "d", "e"];
$a = array_merge(["x"], array_slice($a, 3, 5));

PHP can use a combination of the `array_merge()` and `array_slice()` functions to simulate slice replacement in arrays. In this example the final array will be ['x', 'd', 'e']

Python - Slice String

a = "Cheese fries."
b = a[0:6]

Python uses the `:` operator to get a slice of a string. The number before the colon is the index of the first character of the slice, inclusive. The number after the colon is the index of the the last character of the slice, exclusive. This example slice will return 'Cheese'.

Java - Slice String

String a = "Cheese fries.";
String b = a.substring(0, 6);

Java uses the `.substring()` method to get a string slice. The first argument is the index of the first character of the slice, inclusive. The second argument is the index of the the last character of the slice, exclusive. This example slice will return 'Cheese'.

Javascript - Slice String

var a = "Cheese fries.";
var b = a.slice(0, 6);

Javascript uses the `.slice()` method to get a slice of a string. The first argument is the index of the first character of the slice, inclusive. The second argument is the index of the the last character of the slice, exclusive. This example slice will return 'Cheese'.

C - Slice String

#include <string.h>
...
char a[] = "Cheese fries.";
int size = sizeof(a)/sizeof(a[0]);
char b[size];
memset(b, '', size);
strncpy(b, a, 6);

C can use the `strncpy()` function to copy a specified number of characters from one string to another. Note that in this case we use the `memset()` function to set all bytes of `b` to null before running `strncpy()`. This is to ensure no unwanted data from memory ends up at the end of our new string. This example slice will return 'Cheese'.

PHP - Slice String

$a = "Cheese fries.";
$b = substr($a, 0, 6);

PHP uses the `substr()` function to get a slice of a string. The first argument is the index of the first character of the slice, inclusive. The second argument is the index of the the last character of the slice, exclusive. This example slice will return 'Cheese'.

Python - Uppercase String

x = "hello"
x = x.upper()

Python strings can be made uppercase with the built-in `.upper()` method. Note that this does not change the string in-place.

Java - Uppercase String

String x = "hello";
x = x.toUpperCase();

Java strings can be made uppercase with the `.toUpperCase()` method.

Javascript - Uppercase String

var x = "hello";
x = x.toUpperCase();

Javascript strings can be made uppercase with the `.toUpperCase()` method.

C - Uppercase String

int i = 0;
char str[] = "hello";

while ( str[i] ) {
    str[i] = toupper(str[i]);
    i++;
}

C uses the `toupper()` function to make a single character uppercase, so we can combine that with a loop to make a whole string uppercase.

PHP - Uppercase String

strtoupper("hello");

PHP uses the `strtoupper()` function to make a string uppercase.

Python - Lowercase String

x = "HELLO"
x = x.lower()

Python strings can be made lowercase with the built-in `.lower()` method. Note that this does not change the string in-place.

Java - Lowercase String

String x = "HELLO";
x = x.toLowerCase();

Java strings can be made lowercase with the `.toLowerCase()` method.

Javascript - Lowercase String

var x = "HELLO";
x = x.toLowerCase();

Javascript strings can be made lowercase with the `.toLowerCase()` method.

C - Lowercase String

int i = 0;
char str[] = "HELLO";

while ( str[i] ) {
    str[i] = tolower(str[i]);
    i++;
}

C uses the `tolower()` function to make a single character lowercase, so we can combine that with a loop to make a whole string lowercase.

PHP - Lowercase String

strtolower("HELLO");

PHP uses the `strtolower()` function to make a string lowercase.

Python - Strip Whitespace

x = " Hello "
x = x.strip()

Python uses the `.strip()` method to remove whitespace from both ends of strings.

Java - Strip Whitespace

String x = " Hello ";
x = x.trim();

Java uses the `.trim()` method to remove whitespace from both ends of strings.

Javascript - Strip Whitespace

var x = " Hello ";
x = x.trim();

Javascript uses the `.trim()` method to remove whitespace from both ends of strings.

C - Strip Whitespace

Gone fishin!

C does not have a built-in function to trim whitespace from strings.

PHP - Strip Whitespace

$x = " Hello ";
$x = trim($x);

PHP uses the `trim()` function to remove whitespace from both ends of strings.

Python - Split String to List / Array

x = "a b c d e"
l = x.split()

Python uses the `.split()` method to split a string into a list. By default the string is split on spaces. A string argument can be passed to the `.split()` method to specify a different character to split on.

Java - Split String to List / Array

import java.util.Arrays;
...
String x = "a b c d e;";
String[] a = x.split(" ");
List<String> b = Arrays.asList(a);

Java uses the `.split()` method to split a string into an array. The argument passed to the `.split()` method specifies the character to split on. The array can be converted to a list using the `Arrays.asList()` method.

Javascript - Split String to List / Array

var x = "a b c d e";
var a = x.split(" ");

Javacript uses the `.split()` method to split a string into an array. The argument passed to the `.split()` method specifies the character to split on.

C - Split String to List / Array

Gone fishin!

C does not have a built-in function to split a string into a list.

PHP - Split String to List / Array

$x = "a b c d e";
$a = explode(" ", $x);

PHP uses the `explode()` function to split a string into an array. The first argument passed to the `.split()` method specifies the character to split on. The second argument is the string to split.

Python - Random Number

import randint from random
randint(0, 9)

Python uses the `random.randint()` function to generate a random number between two endpoints, inclusive. This example will generate a number between 0 and 9.

Java - Random Number

import java.util.Random;
...
Random r = new Random();
int i = r.nextInt(10);

Java uses the `nextInt()` method from the `Random` package to generate a random integer ranging from zero to one minus the argument supplied. This example will generate a number between 0 and 9.

Javascript - Random Number

var x = Math.floor(Math.random() * 10);

Javascript uses `Math.random()` to generate a floating point value between 0 and 1, which can be multiplied the desired upper bound and floored using `Math.floor()` to generate a whole integer. This example will generate a number between 0 and 9.

C - Random Number

#include <stdlib.h>
#include <time.h>
...
srand(time(0));
int l = 0;
int h = 9;
int x = (rand() % (h-l+1)) + l;

C uses the `rand()` function to generate a random number. However, to generate a different number each run, it needs to be seeded using the `srand()` function. In this example we use the current time as the seed, via the `time(0)` function call. This example will generate a number between 0 and 9.

PHP - Random Number

$x = rand(0, 9);

PHP uses the `rand()` function to generate a random number between two bounds. This example will generate a number between 0 and 9.

Git - Init

git init

The `git init` command is used to initialize a Git repository. Whatever directory you run this command from will be configured as the root of a new Git project. Behind the scenes, `git init` creates the hidden `.git` folder in the current directory. This contains the information Git uses to track your project.

Git - Clone

git clone https://website.com/repo.git

The `git clone` command is used to copy a Git repository from a remote location to a new directory on your local machine. It also creates remote tracking branches for each of the branches cloned from the source repository.

Git - Add

git add <filename>

The `git add` command is used to stage a file or set of files to be included in the next commit.

Git - Commit

git commit -m "Initial commit."

The format of the `git commit` command is the most commonly used. It creates a new commit on the current branch with a custom commit message. The files committed are those that were previously added to the staging area using the `git add` command.

Git - Push

git push

The `git push` command copies a set of commits from the currently active local Git branch to a remote Git branch.

Git - Pull

git pull

The `git pull` command copies a set of commits from a remote Git branch to the currently active local Git branch.

Git - Create Branch

git branch <new-branch-name>

The `git branch ...` command is used to create a new branch in the local Git repository.

Git - Checkout Branch

git checkout <branch-name>

The `git checkout` command is used to checkout an existing branch. This updates the working directory files and directories to match those of the checked out branch.

Git - Merge Branch

git merge <branch-name>

The `git merge` command merges the specified branch into the currently active branch. If there are no conflicting changes between files, Git will perform the merge automatically. If there are conflicts, Git will direct the user to resolve the conflicts before completing the merge.

Git - Log

git log

The `git log` command is used to show a scrollable list of commits on the currently active branch.

Git - Status

git status

The `git status` command outputs some basic information about the state of the Git project. It lets you know what the currently active branch is, whether it is up to date with it's corresponding remote tracking branch, and whether any files in the working directory have been modified or added to the staging area.

Code Card

The Code Syntax Dictionary