在标头中声明函数

//MyFunctions.h
int myFunction1(int,int);
int myFunction2(int,int);

在MyFunctions.cpp中实现它们

Implement them in MyFunctions.cpp

//MyFunctions.cpp
#include "MyFunctions.h"
int myFunction1(int a, int b){
    //your code
}
int myFunction2(int a, int b){
    //your code
}

将标题包含在所需的任何文件中

Include the header in whatever file you want

//OtherFile.cpp
#include "MyFunctions.h"
//Now you have access to the functions defined in MyFunctions.h in this file

我不知道miniGW，但是它看起来应该像g ++ otherfile.cpp MyFunctions.cpp ...

I dont know miniGW but it should look something like g++ otherfile.cpp MyFunctions.cpp ...