加减除计算器代码出错

#include<stdio.h>
int main()
{
double a, b;
char o;
double h;
printf("请输入\n");
scanf_s("%lf%c%lf", &a, &o, &b);

    if (o == '+')
        h = a + b;
    else if (o == '-')
        h = a - b;
    else if (o == '/')
        h = a / b;
    else
        printf("输入错误\n");

printf("%f",h);
return 0;

命令栏输入1+2以后就是这样了

输入语句：scanf_s("%lf%c%lf", &a, &o, &b); 修改为：scanf_s("%lf%c%lf", &a, &o, 1, &b);