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。
1 #include <iostream> 2 3 /* run this program using the console pauser or add your own getch, system("pause") or input loop */ 4 using namespace std; 5 6 //参数为函数指针的函数 7 int get_result(int a, int b, int (*sub)(int,int)) 8 { 9 int r; 10 r=sub(a,b); 11 return r; 12 } 13 14 //计算最大值 15 int max(int a, int b) 16 { 17 cout<<"In max"<<endl; 18 return((a > b) ? a: b); 19 } 20 21 //计算最小值 22 int min(int a, int b) 23 { 24 cout<<"In min"<<endl; 25 return((a < b) ? a: b); 26 } 27 28 //求和 29 int sum(int a, int b) 30 { 31 cout<<"In sum"<<endl; 32 return(a+b); 33 } 34 35 36 int main(int argc, char** argv) { 37 int a,b,result; 38 39 //测试3次 40 for (int i=1;i<=3;i++) { 41 cout<<"Input a and b :"; 42 cin>>a>>b; 43 44 cout<<i<<"\tget_result("<<a<<","<<b<<", &max):"<<endl; 45 result =get_result(a, b, &max); 46 cout<<"Max of "<<a<<" and "<<b<<" is "<<result<<endl; 47 48 result = get_result(a, b, &min); 49 cout<<"Min of "<<a<<" and "<<b<<" is "<<result<<endl; 50 51 result = get_result(a, b, &sum); 52 cout<<"Sum of "<<a<<" and "<<b<<" is "<<result<<endl; 53 } 54 55 return 0; 56 }
