稍微改了一下
#include<stdio.h>
#include<math.h>
#include<process.h>


double num1,num2;

double add(double x,double y)
{
    return x+y;
}

double cut(double x,double y)
{
    return x-y;
}

double ride(double x,double y)
{
    return x*y;
}

double Remov(double x,double y)
{
    double z;
    if(y==0) printf("eorro 除数不能为0\n");
    z=x/y;
    return z;
}

double (*p[4])(double,double)={add,cut,ride,Remov};//函数指针数组

void input()
{
    system("cls");
    printf("请你输入第一个数：");
    scanf("%lf",&num1);
    printf("请你输入第二个数：");
    scanf("%lf",&num2);   
    return;
}

int main(int argc, char **argv)
{
    int n;
    do{
        printf("\n");
        printf("------计算系统--(ィ+ /厶 BY0.02)-----\n");
        printf("=====================================\n");
        printf("          1. 加法运算\n\n");
        printf("          2. 减法运算\n\n");
        printf("          3. 乘法运算\n\n");
        printf("          4. 除法运算\n\n");
        printf("          5. 退出运算\n\n");
        printf("=====================================\n");
        printf("请选择(1~5):\n");
        scanf("%d",&n);
        
        if(n<=4&&n>=1)
        {
            input();
            printf("结果是：%lf\t\n",p[n-1](num1,num2));
        }
        else if(n==5)
        {
            exit(0);
        }else
        {
            system("cls");
            printf("---ERROR----\n");
        }
    }while(n<=6);
    system("pause");
    return 0;
}

有你这样的吗