C++ File Extensions

File extensions tell both the computer and the programmer what kind of file we're working with. For C++ programs, we typically use .cpp, but there are several related extensions you might encounter:

Common C++ Extensions

• .cpp - Main C++ source files (most common)
• .cc - Alternative C++ source extension (common in Linux)
• .h or .hpp - Header files (we'll learn about these later)
• .c - C language source files (C++ is based on C)

The main difference is how your computer and IDE treat these files:

1// main.cpp - will be compiled as C++
2#include <iostream>
3using namespace std;
4
5int main() {
6  cout << "This is a C++ program!";
7}

If we saved the exact same code as main.txt:

• The IDE won't syntax highlight it properly
• The compiler won't recognize it as code
• We can't build and run it directly

Why Extensions Matter

The extension tells your development tools:

• Which syntax highlighting to use
• Whether the file should be compiled
• Which compiler settings to use
• Which language rules to enforce

For example, saving a C++ file as .c might cause issues:

1// main.c - compiler will treat this as C code
2
3// C doesn't have iostream!
4#include <iostream>  
5
6int main() {
7  // cout doesn't exist in C
8  std::cout << "This won't compile as C!";  
9}

Different Extensions for Different Tools

Some IDEs create additional files with their own extensions:

• .sln - Visual Studio solution files
• .vcxproj - Visual Studio project files
• .o or .obj - Compiled object files
• .exe - Windows executable (the final program)

For now, just remember to save your C++ code files with the .cpp extension - this ensures your development environment will treat them properly as C++ source code.