函数名之后不要留空格，紧跟左括号‘（’，以与关键字区别

函数名之后不要留空格，紧跟左括号‘（’，以与关键字区别。

#include <iostream>

/* run this program using the console pauser or add your own getch, system("pause") or input loop */
using namespace std;

//参数为函数指针的函数
int get_result(int a, int b, int (*sub)(int,int))
{
    int r;
    r=sub(a,b);
    return r;
}
 
//计算最大值
int max(int a, int b)
{
    cout<<"In max"<<endl;
    return((a > b) ? a: b);
}

//计算最小值
int min(int a, int b)
{
    cout<<"In min"<<endl;
    return((a < b) ? a: b);
}

//求和
int sum(int a, int b)
{
    cout<<"In sum"<<endl;
    return(a+b);
}


int main(int argc, char** argv) {
    int a,b,result;

    //测试3次
    for (int i=1;i<=3;i++) {
        cout<<"Input a and b :";
        cin>>a>>b;

        cout<<i<<"	get_result("<<a<<","<<b<<", &max):"<<endl;
        result =get_result(a, b, &max);
        cout<<"Max of "<<a<<" and "<<b<<" is "<<result<<endl;
   
        result = get_result(a, b, &min);
        cout<<"Min of "<<a<<" and "<<b<<" is "<<result<<endl;

        result = get_result(a, b, &sum);
        cout<<"Sum of "<<a<<" and "<<b<<" is "<<result<<endl; 
    }

    return 0;
}