刚刚才开始学！！#include <stdio.h>
int main(void)
{
    int a,b,c;
    char x;
    fprintf(stdout,"请输入内容\n");
    fscanf(stdin,"%d%c%d",&a,&x,&b);
   
    if (x=='+')
    {
        c=a+b;
        fprintf(stdout,"两数之和得\n%d+%d=%d",a,b,c);
    }
   
    if (x=='-')
    {
        c=a-b;
        fprintf(stdout,"两数之差得\n%d-%d=%d",a,b,c);
    }

    else
    {
        fprintf(stdout,"无法运算");
    }
return 0;
}

else if (x=='-')

刚学 就用读写文件的函数