C++ Debugging
Debugging
Debugging is the process of finding and fixing bugs and errors in your program.
Bugs are mistakes that make your program crash, behave incorrectly, or give the wrong output.
Before you start debugging, make sure your code is clean and organized:
- Use proper indentation to keep the structure clear.
- Give your variables clear, meaningful names that describe what they store.
Clean code is easier to read - and easier to debug!
In the sections below, we'll introduce several common debugging techniques.
1. Print Debugging
Use cout to print values and check what's happening in your code.
int x = 10;
int y = 0;
cout << "Before division\n"; // Debug output
int z = x / y; // Crashes!
cout << "After division\n"; // Never runs
If you don't see "After division", the program crashed at x / y.
2. Check Variable Values
Print variables to see if they are what you expect:
int a = 10;
int b = 5;
int result = a - b;
cout << "Result: " <<
result << "\n"; // Result: 5
Expected 15? That means the logic is wrong - try using a + b instead.
3. Use a Debugger Tool
IDEs like Visual Studio, Code::Blocks, and VS Code have debuggers that let you:
- Pause your program (breakpoints)
- Step through code line by line
- Watch variables and find unexpected values
Tip: Start with "1. Print Debugging". Use IDE tools as you get more comfortable.
4. Learn from Error Messages
The C++ compiler and runtime errors often tell you what went wrong and where. For example:
error: expected ';' before 'return'
Easy solution: Fix the missing semicolon!
Exception Handling
While debugging is about finding and fixing errors in your code, exception handling is a way to deal with errors while the program is running - and run specific code when something goes wrong.
Learn about Exception Handling in the next chapter.
