1.宏变量

2.条件宏

#include <iostream>
#define aa 30
#define version 2using namespace std;/** 1.宏变量* 2.条件宏* */int main() {cout << aa << endl;#if version > 1cout<< "升级版本"<<endl;
#elsecout << "不升级"<<endl;
#endifreturn 0;
}