c - 预处理器和宏

Question

#include <stdio.h>
#define macro(n, a, i, m) m##a##i##n
#define MAIN macro(n, a, i, m)
int MAIN()
{

    printf("GeeksQuiz");

    return 0;
}

大家好在这个问题中，输出是 geeksquiz，因为它说 main 首先被宏替换，然后再次替换。实际更换在哪里进行？不就是定义函数吗？谢谢您

Answer 1

这发生在编译器翻译的第四阶段(称为预处理阶段)。

您可以阅读“Phases of Translation”

If there was some other name of the function other than macro , would it have done the same or defined it as different functions

是的。 “宏”可以更改为其他名称。

#define some_other_name(n, a, i, m) m##a##i##n
#define MAIN some_other_name(n, a, i, m)

How do we know when the main function is getting replaced. In cases ive seen that they are defined as separate functions, is it due to macro or MAIN ? ( Sorry new to C here )

因为 MAIN 被定义为 MACRO，并且 MACRO 扩展导致 main。