一,//条件预编译处理
#define DEBUG
#include<iostream>
using std::cout;
int main()
{
#ifdef DEBUG
cout<<"调试信息\n";
#endif
cout<<"程序输出\n";
return 0;
#define PI 3.1415 //不带参数的预处理
#define ADD(x,y) (x)+(y)//带参数的预处理
#include<iostream>
using std::cout;
using std::endl;
int main()
{
int r(10);
cout<<"面积:"<<r*r*PI<<endl;
cout<<"两个数的和:"<<ADD(3,4)<<endl;
return 0;
#include<iostream>
using std::cout;
using std::endl;
int main()
{
int r(5);
cout<<"5的平方是:"<<r*r<<endl;
return 0;
}
#define DEBUG
#include<iostream>
using std::cout;
int main()
{
#ifdef DEBUG
cout<<"调试信息\n";
#endif
cout<<"程序输出\n";
return 0;
}
2,
#define PI 3.1415 //不带参数的预处理
#define ADD(x,y) (x)+(y)//带参数的预处理
#include<iostream>
using std::cout;
using std::endl;
int main()
{
int r(10);
cout<<"面积:"<<r*r*PI<<endl;
cout<<"两个数的和:"<<ADD(3,4)<<endl;
return 0;
}
3,
#include<iostream>
using std::cout;
using std::endl;
int main()
{
int r(5);
cout<<"5的平方是:"<<r*r<<endl;
return 0;
}