C程序设计的#define？

本文介绍了C程序设计的#define？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

#include<stdio.h>
#include<conio.h>

#define SQ(x) x*x

void main()
{
   int a1 , a2;
   int b1 , b2;

   a1 = 2;
   a2 = 2;

   b1 = 0;
   b2 = 0;

   b1 = SQ(a1++);
   b2 = SQ(++a2);

   printf("Frist = %d",b1);
   printf("Second = %d",b2);
}

I know what is the output of the code.

as #define work in other programethat way it is not working in above codeWhy.?

解决方案

The result of an expression with more than one ++ operator on the same variable is officially an undefined behavior in C.

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