宏的举例

#include <iostream>#include <string>using namespace std;#define PI 3.141592657#define TEST "hello"#define MAX(a,b) (a>b?a:b)//宏函数#define MUL(a,b) (a*b)#define SafeDeleteArry(p) \    if(p != NULL)\    {            \    delete p;    \    p = NULL;    \    }void main(){    cout<<100 * PI <<endl;    cout<<TEST<<endl;    cout<<MAX(10,20)<<endl;    cout<<MUL(10,20)<<endl;    cout<<MUL(10+10,20+20)<<endl;    char* p = new char[10];    SafeDeleteArry(p);//    if(p != NULL)//    {//    }}