switch 函数加减乘除

int main()
{
   // char ch;
    int a=10;
    int b=20;
    printf("please enter the calculation you wantn");
    char ch=getchar();
    switch(ch)
    {
            case '+':printf("a+b=%dn",action1(a,b));break;
            case '-':printf("a-b=%dn",action2(a,b));break;
            case '*':printf("a*b=%dn",action3(a,b));break;
            case '/':printf("a/b=%dn",action4(a,b));break;
            default:putchar('a');
    }

    return 0;
}

int action1(int x,int y)
{
    return  x+y;
}

int action2(int x,int y)
{
    return  x-y;
}

int action3(int x,int y)
{
        return x*y;

}

int action4(int x,int y)
{
        return x/y;
}