How to use a C++ header file?

1 year ago
Ava Mitchell
2 minutes

The usage method of C++ header files is as follows:

  1. Include this in the code.
  2. Could you please repeat that in English?
  3. header file

For example, to include a header file named myheader.h, you can use the following command:

#include "myheader.h"
  1. Definition of a header file: In a header file, functions, classes, constants, macros, etc. are defined. A header file only contains declarations and definitions, it does not include specific implementations.

For example, the following functions can be defined in myheader.h.

// 函数声明
int add(int a, int b);

// 类定义
class MyClass {
public:
    void printMessage();
};
  1. By using the declarations in the header file, you can utilize functions, classes, constants, etc. in the source file. Simply include the necessary header file in the source file to access the declarations within it.

For example, using the add function and MyClass class in the source file:

#include "myheader.h"

int main() {
    int result = add(2, 3);
    MyClass obj;
    obj.printMessage();
    return 0;
}

Reminder:

  1. The declaration in the header file should be placed at the top of the header file so that other files can directly see it.
  2. Header files should use include guards or pragma once to prevent multiple inclusions.
  3. Header files should only include necessary declarations to reduce compile time and potential naming conflicts.
  4. Multiple source files can share the same header file to reuse code.
  5. Include other header files in the header file to import other dependencies. It is important to ensure the correct order of the included header files to avoid dependency errors.
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