Header and Source Files in Programming | C++ | QT | Include Guards and Best Practices | Lesson 10
In this video, I explained source and header files. In C++, the code is often split into two types of files: header files (typically with the `.h` or `.hpp` extension) and source files (typically with the `.cpp` extension). This separation helps organize code, makes it more maintainable, and allows for code reuse.
Header Files (`.h` or `.hpp`)
Header files are meant to declare the structure and properties of your classes, functions, and constants. Here's what they typically contain:
1. Function Declarations (Prototypes): Declares functions that are implemented in the source files. This tells the compiler about the function's name, return type, and parameters, without needing the actual function code (implementation).
2. Constants: Constants that are shared between multiple source files may be declared in a header.
3. #include Guards: To prevent double inclusion of the same header file, which can lead to errors, `#include` guards or `#pragma once` directive is often used.
Source Files (`.cpp`)
Source files contain the actual implementation (definitions) of the functions, methods, and templates declared in the header files. Here's what they usually contain:
1. Function Definitions: The actual code of the functions declared in the header.
2. Main Function: Every C++ program must have one `main` function, which is the entry point of the program. It's usually found in one of the `.cpp` files.
3. #include Statements: Source files include the header files to use the declarations. They might also include other headers like standard library headers.
Best Practices
Use #include Guards in Headers: Prevents double inclusion.
Keep Headers Clean: Include only what's necessary in a header file. This reduces dependencies and improves compilation time.
Function Definitions in Source Files: Except for templates and inline functions, define functions in source files to hide implementation details and reduce compilation dependencies.
By separating declaration and definition, C++ allows for cleaner code structure, faster compilation times (since changes in a source file won't necessarily require recompiling other files that include its header), and easier management and readability of code.