终于跑起来了，含自定义 include .h 的c语言程序，超开心呀！

header files contain prototypes for functions you define in a .c or .cpp/.cxx file (depending if you're using c or c++).

You want to place #ifndef/#defines around your .h code so that if you include the same .h twice in different parts of your programs, the prototypes are only included once

 这本c语言的书不错，学习之，加油！！！ 

参考：

 

 

foo.h #ifndef FOO_H_ /* Include guard */#define FOO_H_ int foo(int x); /* An example function declaration */ #endif // FOO_H_ foo.c #include "foo.h" /* Include the header (not strictly necessary here) */ int foo(int x) /* Function definition */ { return x + 5; } main.c #include #include "foo.h" /* Include the header here, to obtain the function declaration */ int main(void) { int y = foo(3); /* Use the function here */ printf("%d\n", y); return 0; } To compile using GCC gcc -o my_app main.c foo.c