编写一个c++的代码可以实现以下要求，歌手比赛系统对一次歌手比赛的成绩进行管理，功能要求:1、依次输入每个选手的编号、姓名、十个评委的成绩，根据输入计算出总成绩和平均成绩(去掉最高分，去掉最低分)。2、显示主菜单如下:1)输入选手数据2)评委打分3)成绩排序(按平均分)4)数据查询5追加学生数据6退出系统)

以下实现以上要求的 C 代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_NUM 50
#define MAX_NAME_LEN 20

struct contestant
{
    int id;                     // 选手编号
    char name[MAX_NAME_LEN];    // 选手姓名
    float score[10];            // 评委打分
    float total_score;          // 总成绩
    float avg_score;            // 平均成绩
};

struct contestant contestants[MAX_NUM];    // 存储所有选手的数组
int num_contestants = 0;                   // 当前选手数量

// 打印主菜单
void print_menu()
{
    printf("主菜单\n");
    printf("1) 输入选手数据\n");
    printf("2) 评委打分\n");
    printf("3) 成绩排序(按平均分)\n");
    printf("4) 数据查询\n");
    printf("5) 追加选手数据\n");
    printf("6) 退出系统\n");
}

// 输入选手数据
void input_contestant_data()
{
    int i, j;
    printf("请输入选手数量：");
    scanf("%d", &num_contestants);
    for (i = 0; i < num_contestants; i++)
    {
        printf("请输入第%d个选手的编号、姓名：", i+1);
        scanf("%d %s", &contestants[i].id, contestants[i].name);
        contestants[i].total_score = 0;
        contestants[i].avg_score = 0;
        for (j = 0; j < 10; j++)
        {
            printf("请输入第%d个选手第%d个评委的成绩：", i+1, j+1);
            scanf("%f", &contestants[i].score[j]);
            contestants[i].total_score += contestants[i].score[j];
        }
        // 计算平均成绩
        float max_score = contestants[i].score[0];
        float min_score = contestants[i].score[0];
        for (j = 1; j < 10; j++)
        {
            if (contestants[i].score[j] > max_score)
            {
                max_score = contestants[i].score[j];
            }
            if (contestants[i].score[j] < min_score)
            {
                min_score = contestants[i].score[j];
            }
        }
        contestants[i].avg_score = (contestants[i].total_score - max_score - min_score) / 8;
    }
}

// 评委打分
void judge_scoring()
{
    int contestant_id, judge_id;
    float score;
    printf("请输入评分选手的编号：");
    scanf("%d", &contestant_id);
    printf("请输入评分评委的编号：");
    scanf("%d", &judge_id);
    printf("请输入评分：");
    scanf("%f", &score);
    contestants[contestant_id-1].score[judge_id-1] = score;
    // 重新计算总成绩和平均成绩
    float max_score = contestants[contestant_id-1].score[0];
    float min_score = contestants[contestant_id-1].score[0];
    contestants[contestant_id-1].total_score = 0;
    int j;
    for (j = 0; j < 10; j++)
    {
        contestants[contestant_id-1].total_score += contestants[contestant_id-1].score[j];
        if (contestants[contestant_id-1].score[j] > max_score)
        {
            max_score = contestants[contestant_id-1].score[j];
        }
        if (contestants[contestant_id-1].score[j] < min_score)
        {
            min_score = contestants[contestant_id-1].score[j];
        }
    }
    contestants[contestant_id-1].avg_score = (contestants[contestant_id-1].total_score - max_score - min_score) / 8;
}

// 成绩排序
void sort_contestants_by_score()
{
    int i, j, max_index;
    struct contestant temp;
    // 冒泡排序
    for (i = 0; i < num_contestants-1; i++)
    {
        max_index = i;
        for (j = i+1; j < num_contestants; j++)
        {
            if (contestants[j].avg_score > contestants[max_index].avg_score)
            {
                max_index = j;
            }
        }
        if (max_index != i)
        {
            temp = contestants[i];
            contestants[i] = contestants[max_index];
            contestants[max_index] = temp;
        }
    }
}

// 数据查询
void query_contestant_data()
{
    int contestant_id;
    printf("请输入要查询的选手编号：");
    scanf("%d", &contestant_id);
    printf("选手编号：%d\n", contestants[contestant_id-1].id);
    printf("选手姓名：%s\n", contestants[contestant_id-1].name);
    printf("选手成绩：\n");
    int i;
    for (i = 0; i < 10; i++)
    {
        printf("%.1f ", contestants[contestant_id-1].score[i]);
    }
    printf("\n");
    printf("选手总成绩：%.1f\n", contestants[contestant_id-1].total_score);
    printf("选手平均成绩：%.1f\n", contestants[contestant_id-1].avg_score);
}

// 追加选手数据
void append_contestant_data()
{
    int i, j, num_new_contestants;
    printf("请输入要追加的选手数量：");
    scanf("%d", &num_new_contestants);
    for (i = num_contestants; i < num_contestants+num_new_contestants; i++)
    {
        printf("请输入第%d个选手的编号、姓名：", i+1);
        scanf("%d %s", &contestants[i].id, contestants[i].name);
        contestants[i].total_score = 0;
        contestants[i].avg_score = 0;
        for (j = 0; j < 10; j++)
        {
            printf("请输入第%d个选手第%d个评委的成绩：", i+1, j+1);
            scanf("%f", &contestants[i].score[j]);
            contestants[i].total_score += contestants[i].score[j];
        }
        // 计算平均成绩
        float max_score = contestants[i].score[0];
        float min_score = contestants[i].score[0];
        for (j = 1; j < 10; j++)
        {
            if (contestants[i].score[j] > max_score)
            {
                max_score = contestants[i].score[j];
            }
            if (contestants[i].score[j] < min_score)
            {
                min_score = contestants[i].score[j];
            }
        }
        contestants[i].avg_score = (contestants[i].total_score - max_score - min_score) / 8;
    }
    num_contestants += num_new_contestants;
}

int main()
{
    int choice;
    do
    {
        print_menu();
        printf("请输入选项：");
        scanf("%d", &choice);
        switch (choice)
        {
        case 1:
            input_contestant_data();
            break;
        case 2:
            judge_scoring();
            break;
        case 3:
            sort_contestants_by_score();
            printf("排名\t编号\t姓名\t平均成绩\n");
            int i;
            for (i = 0; i < num_contestants; i++)
            {
                printf("%d\t%d\t%s\t%.1f\n", i+1, contestants[i].id, contestants[i].name, contestants[i].avg_score);
            }
            break;
        case 4:
            query_contestant_data();
            break;
        case 5:
            append_contestant_data();
            break;
        case 6:
            printf("感谢使用！\n");
            break;
        default:
            printf("无效选项！\n");
            break;
        }
    } while (choice != 6);

    return 0;
}

使用方法：编译并运行程序，在菜单中输入相应选项即可。