#include<stdio.h>
int add(int a,int b)
{
    int c;
    c=a+b;
    return(c);

}
int jian(int a, int b)
{
     int c;
     c=a-b;
     return(c);
}
int  cheng(int a,int b)
{
    int c;
    c=a*b;
    return(c);
}
int  chu(int a, int b)
{
    int c;
    c=a/b;
    return (c);
}


int  ys(int a, int b)
{
    int c;
    c=a%b;
    return c;
}

     
void main()
{
    int a,b,c;
    char f;
    printf("please  input  运算符:\n");
    scanf("%c",&f);
    printf("please   input  number:\n");
    scanf("%d  %d ",&a,&b);
    switch('f')
    {
    case'+':  c = add(a,b);break;
    case'-':  c = jian(a,b);break;
    case'*':  c = cheng(a,b);break;
    case'/':  c = chu(a,b); break;
    case'%':  c = ys(a,b);break;
    }
    printf ("the resule  is: %d",c);
}

switch（'f'）？？

#include<stdio.h>
int add(int a,int b)
{
    return a+b;
}
int jian(int a, int b)
{
     return a-b;
}
int  cheng(int a,int b)
{
    return a*b;
}
int  chu(int a, int b)
{
    return a/b;
}

int  ys(int a, int b)
{
    return a%b;
}   

void main()
{
    int a,b,c;
    char f;
    printf("please  input  运算符:\n");
    scanf("%c",&f);
    printf("please   input  number:\n");
    scanf("%d  %d ",&a,&b);
    switch(f)//这要改
    {
    case'+':  c = add(a,b);break;
    case'-':  c = jian(a,b);break;
    case'*':  c = cheng(a,b);break;
    case'/':  c = chu(a,b); break;
    case'%':  c = ys(a,b);break;
    }
    printf ("the resule  is: %d\n",c);
}
[local]1[/local]

要有截止输入的符号

#include<stdio.h>
#include<stdlib.h>

int add(int a,int b)
{
    int c;
    c=a+b;
    return c;
}

int jian(int a, int b)
{
     int c;
     c=a-b;
     return c;
}

int  cheng(int a,int b)
{
    int c;
    c=a*b;
    return c;
}

int  chu(int a, int b)
{
    int c;
    c=a/b;
    return c;
}


int  ys(int a, int b)
{
    int c;
    c=a%b;
    return c;
}

     
int main()
{
    int a,b,c;
    int f;                            //switch括号内只能是整型变量，所以f要定义为整型
    printf("please  input  运算符:\n");
    scanf("%d",&f);
    printf("please   input  number:\n");
    scanf("%d,%d",&a,&b);            //输入两个数之间不要用空格，用逗号最好，用空格运行输入的时候不好把握
    switch(f)                        //这个括号内一定要是整型变量，你这里犯了两个错误：第一，f不能用单引号括起来；第二：不能是字符型
    {
    case 1:  c = add(a,b);break;           //下面几条语句相应的改为1-5
    case 2:  c = jian(a,b);break;
    case 3:  c = cheng(a,b);break;
    case 4:  c = chu(a,b); break;
    case 5:  c = ys(a,b);break;
    }
    printf ("the resule  is: %d",c);
    system("pause");
    return 0;
}

谢谢亲们啦