这是我编的。不知道行不行?
#include"stdio.h"
int main()
{
    int score[5][7], sum[5], sun[7]; 
    int i, j, m = 1, n = 1, max, min, sim = 0, sin = 0;
    int xue[5];
    for (i = 1; i < 5; i++)
    {
    printf("请输入第%d个学生的学号及六次成绩\n", i);
        scanf("%d", &xue[i]);
        for (j = 1; j < 7; j++)
            scanf("%d", &score[i][j]);
    }
    for (i = 1; i < 5; i++)
    {
        for (j = 1; j < 7; j++)
            sim = sim + score[i][j];
        sum[i] = sim;
        sim = 0;
    }
    for (i = 1; i < 7; i++)
    {
        for (j = 1; j < 5; j++)
            sin = sin + score[j][i];
        sun[i] = sin;
        sin = 0;
    }
    max = sum[1];
    min = sum[1];
    for (i = 1; i < 5; i++)
    {
        if (sum[i] > max)
        {
            max = sum[i];
            m = i;
        }
    }
    for (i = 1; i < 5; i++)
    {
        if (sum[i] < min)
        {
            min = sum[i];
            n = i;
        }
    }
    printf("总分最高学生为%d\n总分最低学生为%d\n", xue[m],
           xue[n]);
    printf("请输入学生学号\n");
    scanf("%d", &m);
    for (i = 1; i < 5; i++)
    {
        if (m == xue[i])
       {
           for (j = 1; j < 7; j++)
                printf("该生第%d次考试成绩为%d\n", j, score[i][j]);
            printf("该生平均成绩为%f\n", (float)sum[i] / 6);
           }
    }
    printf("请输入考试考试次数\n");
    scanf("%d", &n);
    for (i = 1; i < 5; i++)
   {
        printf("学号为%d", xue[i]);
        printf("成绩为%d\n", score[i][n]);
    }
    printf("该次平均成绩为%f", (float)sun[n] / 4);
    return 0;
}
改错的话很好改。楼主自己加个if else吧!!!