RT，是我的getchar使用有问题吗？

代码：

#include <cstdio>
#define INF 0x7fffffff

int num[3], max, Pmax, min = INF, Pmin, mid;//Pmax为最大数位置，Pmin为最小数位置
char opt;

int main (void) {
    for (int i = 0; i < 3; i ++) {
        scanf ("%d", &num[i]);
        if (num[i] > max) {
            max = num[i];
            Pmax = i;
        }
        if (num[i] < min) {
            min = num[i];
            Pmin = i;
        }
    }
    for (int i = 0; i < 3; i ++)
        if (i != Pmax && i != Pmin)//不是最大不是最小
            mid = num[i];
    getchar ();//把中间空格吃掉
    for (int i = 0; i < 3; i ++) {
        opt = getchar ();//读入option
        if (opt == 'A')
            printf ("%d", min);
        else if (opt == 'B')
            printf ("%d", mid);
        else if (opt == 'C')
            printf ("%d", max);
        else
            printf ("Wrong Input!\n");
        if (i < 2)
            putchar (' ');//中间填空格
    }
    return 0;
}