C语言求助，利用函数的指针变量，输入两个数选择四则运算中的一种进行运算？

Question

如题所述

Answer 1

#include <stdio.h>

#include <stdlib.h>

double my_add(double a, double b) { return a + b; }

double my_sub(double a, double b) { return a - b; }

double my_mul(double a, double b) { return a * b; }

double my_div(double a, double b) { return a / b; }

typedef double (*cal_fp)(double a, double b);

double my_cal(double a, double b, cal_fp fp)

{

    return fp(a, b);

}

int main()

{

    double a, b, r;

    char sign;

    scanf("%lf %c %lf", &a, &sign, &b);

    switch(sign)

    {

        case '+': r = my_cal(a, b, my_add); break;

        case '-': r = my_cal(a, b, my_sub); break;

        case '*': r = my_cal(a, b, my_mul); break;

        case '/': r = my_cal(a, b, my_div); break;

    }

    printf("%lf %c %lf = %lf\n", a, sign, b, r);

    return 0;

}

---

Answer 2