Print first letter of each word in a string using regex

Try it on GfG Practice

Given a string, extract the first letter of each word in it. "Words" are defined as contiguous strings of alphabetic characters i.e. any upper or lower case characters a-z or A-Z. Examples:

Input : Geeks for geeks
Output :Gfg
        
Input : United Kingdom
Output : UK

Below is the Regular expression to extract the first letter of each word. It uses '/b'(one of boundary matchers). Please refer How to write Regular Expressions? to learn it.

\b[a-zA-Z]

// Java program to demonstrate extracting first
// letter of each word using Regex

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Test 
{
    public static void main(String[] args) 
    {
        String s1 = "Geeks for Geeks";
        String s2 = "A Computer Science Portal for Geeks";
        
        Pattern p = Pattern.compile("\\b[a-zA-Z]");
        
        Matcher m1 = p.matcher(s1);
        Matcher m2 = p.matcher(s2);
        
        System.out.println("First letter of each word from string \"" + s1 + "\" : ");
        while (m1.find())
            System.out.print(m1.group());
        
        System.out.println();
        
        System.out.println("First letter of each word from string \"" + s2 + "\" : ");
        
        while (m2.find()) 
            System.out.print(m2.group());
        
        
    }
}

// C# program to demonstrate extracting first
// letter of each word using Regex

using System;
using System.Text.RegularExpressions;

public class GFG
{
    public static void Main()
    {
        string s1 = "Geeks for Geeks";
        string s2 = "A Computer Science Portal for Geeks";
        
        Regex p = new Regex("\\b[a-zA-Z]");
        
        
        Console.WriteLine("First letter of each word from string \"" + s1 + "\" : ");
        foreach (Match ItemMatch in p.Matches(s1))
            Console.Write(ItemMatch.Value);
        
        Console.WriteLine();
        
        Console.WriteLine("First letter of each word from string \"" + s2 + "\" : ");
        
        foreach (Match ItemMatch in p.Matches(s2))
            Console.Write(ItemMatch.Value);
        
    }
}

// This code is contributed by Utkarsh

# Python program to demonstrate extracting first
# letter of each word using Regex
import re

s1="Geeks for Geeks"
s2="A Computer Science Portal for Geeks"

p = re.compile("\\b[a-zA-Z]")

print("First letter of each word from string '{0}' : ".format(s1))

for m1 in re.finditer(p,s1):
    print(m1.group(0),end="")
    
print()

print("First letter of each word from string '{0}' : ".format(s2))

for m2 in re.finditer(p,s2):
    print(m2.group(0),end="")
    

# This code is contributed by Pushpesh Raj.

Output:

First letter of each word from string "Geeks for Geeks" : 
GfG
First letter of each word from string "A Computer Science Portal for Geeks" : 
ACSPfG

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