9.6.c语言编写程序，能够输入100个学生的学号和姓名，并将学生按照学号由小到大排序。当输入一个学号时能用(二分查找)折半查找法找出该学生的姓名。求解bug

//有个bug,学号个位数，不输出姓名。
#include 

#include 

#define NUM 3

int find_num(int num[], int target)
{
    int left = 0;
    int right = NUM-1;//最后一个元素的索引

    while (left <= right)//左闭右闭区间 ->[left,right]
    {
        int mid = left + (right - left) / 2;//为了防止溢出,(right + left ) / 2可能会溢出
        if (num[mid] == target)
		{
            return mid;//找到指定数就立即返回
		}
        else if (num[mid] > target)
            right = mid - 1;
        else if (num[mid] < target)
            left = mid + 1;

    }
    return -1;

}



int main()

{

    int i, j, tmp3,target;

    char name[NUM][10];//姓名

    int num[NUM];//学号

    float score[NUM][3];//三门课成绩

    float sum[NUM];//总成绩

    float tmp, tmp0, tmp1, tmp2;

    char stmp[10];

	int find_num(int num, int target);


    printf("输入姓名、学号和三门课成绩：n");

    for (i = 0; i < NUM; i++)

    {
        printf("请输入第%d个学生的信息：n", i);


        scanf(" %s %d %f %f %f", name[i], &num[i], &score[i][0], &score[i][1], &score[i][2]);
        getchar();
        sum[i] = score[i][0] + score[i][1] + score[i][2];
    }

    for (i = 0; i < NUM - 1; i++)
    {

        for (j = i + 1; j < NUM; j++)
        {

            if (num[i] < num[j])

            {

                tmp0 = score[i][0];

                score[i][0] = score[j][0];

                score[j][0] = tmp0;//交换成绩

                tmp1 = score[i][1];

                score[i][1] = score[j][1];

                score[j][1] = tmp1;//交换成绩

                tmp2 = score[i][2];

                score[i][2] = score[j][2];

                score[j][2] = tmp2;//交换成绩

                tmp = sum[i];

                sum[i] = sum[j];

                sum[j] = tmp;//交换成绩

                tmp3 = num[i];

                num[i] = num[j];

                num[j] = tmp3;//交换成绩

                strcpy(stmp, name[i]);

                strcpy(name[i], name[j]);

                strcpy(name[j], stmp);//交换姓名
            }

        }
    }

    printf("排序后的学生的信息：n");

    for (i = 0; i < NUM; i++)
    {
        printf("%st%dt%ft%ft%fn", name[i], num[i], score[i][0], score[i][1], score[i][2]);
    }

    scanf("%d", &target);
	target=find_num(num,target);
	printf("%s",name[target]);
	system("pause");
    return 0;

}

运行时学号不可以输入一位数，否则会无法输出姓名