C++老九 P79 函数指针

最新推荐文章于 2023-03-16 22:13:40 发布

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本文介绍了一个使用函数指针进行算术运算的C++程序实例。通过定义函数指针并将其指向不同的算术操作，如加、减、乘、除，程序能够根据用户输入的操作符灵活地调用相应的函数来执行计算。此例展示了函数指针在提高代码灵活性和可扩展性方面的作用。

函数指针

#include <iostream>
#include "Cal.h"

using namespace std;

int main()
{   double (*prtCC)(double, double);
    double num1, num2;
    char op;
    cout << "please input 2 num: ";
    cin >> num1 >> num2;
    cout << "input opration:";
    cin >> op;
    switch (op)
    {
        case '+':
            prtCC = adde;
            break;
        case '-':
            prtCC = minuss;
            break;
        case '*':
            prtCC = multi;
            break;
        case '/':
            prtCC = divide;
            break;
        default:
            cout << "quit " << endl;
            break;
    }
    print_result(prtCC, num1, num2);
    return 0;
}

Cal.h 头文件

#ifndef P79_CAL_H
#define P79_CAL_H

#include <iostream>

using namespace std;

//add
double add(double, double);

//minus
double minus(double, double);

//mult
double multi(double, double);

//divide
double divide(double, double);

//print result
void print_result(double (*)(double, double), double, double);

void print_result(double (*prtcal)(double, double), double num1, double num2)   //函数指针
{
    double result = prtcal(num1, num2);
    cout << "result is: " << result << endl;
}


double adde(double num1, double num2)
{
    return num1 + num2;
}


double minuss(double num1, double num2)
{
    return num1 - num2;
}

double multi(double num1, double num2)
{
    return num1 * num2;
}

double divide(double num1, double num2)
{
    if (num2 == 0)
    {
        cout << "error, num2 is 0" << endl;
        return 0;
    }
    return num1 / num2;
}


#endif //P79_CAL_H