c语言结构体实现学生成绩系统，功能包括创建成绩功能：根据键盘输入创建各班学生各学科成绩信息，根据班级查找功能：根据输入的班级信息，查询改班学生的分数信息及班级排名。根据课程查找功能：根据输入的课程名称，查询该课程的均分、学生排名、分数。根据学生查找功能：根据输入的学生信息，查询该生的各科成绩、总分及排名

好的，下面是一个简单的C语言程序，用结构体实现学生成绩管理系统，包括创建成绩、根据班级、课程、学生查找功能：

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

#define MAX_CLASS 5     // 最大班级数
#define MAX_STUDENT 30  // 最大学生数
#define MAX_SUBJECT 3   // 最大科目数

// 学生信息结构体
typedef struct student {
  char name[20];          // 姓名
  int score[MAX_SUBJECT]; // 分数
  int total_score;        // 总分
  int class_no;           // 班级号
  int rank;               // 排名
} Student;

// 班级信息结构体
typedef struct class {
  char name[10];          // 班级名称
  Student students[MAX_STUDENT];  // 学生信息
  int student_num;        // 学生数量
} Class;

// 科目信息结构体
typedef struct subject {
  char name[10];          // 科目名称
  int total_score;        // 科目总分
  int pass_score;         // 及格分数
} Subject;

// 成绩信息结构体
typedef struct score {
  Class classes[MAX_CLASS];   // 班级信息
  int class_num;              // 班级数量
  Subject subjects[MAX_SUBJECT];  // 科目信息
  int subject_num;            // 科目数量
} Score;

// 初始化学生成绩
void init_score(Score *score) {
  // 初始化班级信息
  strcpy(score->classes[0].name, "Class1");
  score->classes[0].student_num = 0;
  score->class_num = 1;

  // 初始化科目信息
  strcpy(score->subjects[0].name, "Math");
  score->subjects[0].total_score = 100;
  score->subjects[0].pass_score = 60;
  strcpy(score->subjects[1].name, "English");
  score->subjects[1].total_score = 100;
  score->subjects[1].pass_score = 60;
  score->subject_num = 2;
}

// 创建成绩
void create_score(Score *score) {
  int class_no, student_no;
  printf("请输入班级号(1-%d): ", score->class_num);
  scanf("%d", &class_no);
  if (class_no < 1 || class_no > score->class_num) {
    printf("班级号输入有误！\n");
    return;
  }

  Class *class = &score->classes[class_no-1];
  printf("请输入学生姓名: ");
  scanf("%s", class->students[class->student_num].name);
  class->students[class->student_num].class_no = class_no;
  for (int i = 0; i < score->subject_num; i++) {
    printf("请输入%s成绩: ", score->subjects[i].name);
    scanf("%d", &class->students[class->student_num].score[i]);
    class->students[class->student_num].total_score += class->students[class->student_num].score[i];
  }
  class->student_num++;
  printf("创建成功！\n");
}

// 根据班级查找
void search_by_class(Score *score) {
  int class_no;
  printf("请输入班级号(1-%d): ", score->class_num);
  scanf("%d", &class_no);
  if (class_no < 1 || class_no > score->class_num) {
    printf("班级号输入有误！\n");
    return;
  }

  Class *class = &score->classes[class_no-1];
  printf("班级名称：%s\n", class->name);
  printf("学生列表：\n");
  for (int i = 0; i < class->student_num; i++) {
    printf("%d. %s\n", i+1, class->students[i].name);
  }
  printf("请输入学生序号(1-%d): ", class->student_num);
  int student_no;
  scanf("%d", &student_no);
  if (student_no < 1 || student_no > class->student_num) {
    printf("学生序号输入有误！\n");
    return;
  }

  Student *student = &class->students[student_no-1];
  printf("%s的成绩：\n", student->name);
  for (int i = 0; i < score->subject_num; i++) {
    printf("%s：%d\n", score->subjects[i].name, student->score[i]);
  }
  printf("总分：%d\n", student->total_score);
  printf("排名：%d\n", student->rank);
}

// 根据课程查找
void search_by_subject(Score *score) {
  char subject_name[10];
  printf("请输入科目名称: ");
  scanf("%s", subject_name);
  int subject_no = -1;
  for (int i = 0; i < score->subject_num; i++) {
    if (strcmp(subject_name, score->subjects[i].name) == 0) {
      subject_no = i;
      break;
    }
  }
  if (subject_no == -1) {
    printf("科目名称输入有误！\n");
    return;
  }

  printf("%s成绩：\n", subject_name);
  double total_score = 0;
  for (int i = 0; i < score->class_num; i++) {
    Class *class = &score->classes[i];
    printf("%s：\n", class->name);
    for (int j = 0; j < class->student_num; j++) {
      Student *student = &class->students[j];
      total_score += student->score[subject_no];
    }
    double avg_score = total_score / class->student_num;
    printf("平均分：%f\n", avg_score);
    printf("排名：\n");
    for (int j = 0; j < class->student_num; j++) {
      Student *student = &class->students[j];
      if (student->score[subject_no] >= score->subjects[subject_no].pass_score) {
        printf("%s：%d\n", student->name, student->score[subject_no]);
      }
    }
  }
}

// 根据学生查找
void search_by_student(Score *score) {
  char name[20];
  printf("请输入学生姓名: ");
  scanf("%s", name);
  printf("学生列表：\n");
  for (int i = 0; i < score->class_num; i++) {
    Class *class = &score->classes[i];
    for (int j = 0; j < class->student_num; j++) {
      Student *student = &class->students[j];
      if (strcmp(name, student->name) == 0) {
        printf("%s %s：%d\n", class->name, student->name, student->total_score);
        printf("各科成绩：\n");
        for (int k = 0; k < score->subject_num; k++) {
          printf("%s：%d\n", score->subjects[k].name, student->score[k]);
        }
        printf("排名：%d\n", student->rank);
        return;
      }
    }
  }
  printf("学生姓名输入有误！\n");
}

// 计算排名
void calc_rank(Score *score) {
  for (int i = 0; i < score->class_num; i++) {
    Class *class = &score->classes[i];
    for (int j = 0; j < class->student_num; j++) {
      Student *student = &class->students[j];
      student->rank = 1;
      for (int k = 0; k < class->student_num; k++) {
        if (k != j && class->students[k].total_score > student->total_score) {
          student->rank++;
        }
      }
    }
  }
}

int main() {
  Score score;
  init_score(&score);
  int choice;
  do {
    printf("1. 创建成绩\n");
    printf("2. 根据班级查找\n");
    printf("3. 根据课程查找\n");
    printf("4. 根据学生查找\n");
    printf("0. 退出程序\n");
    printf("请输入选择(0-4): ");
    scanf("%d", &choice);
    switch (choice) {
      case 1:
        create_score(&score);
        break;
      case 2:
        search_by_class(&score);
        break;
      case 3:
        search_by_subject(&score);
        break;
      case 4:
        search_by_student(&score);
        break;
      case 0:
        printf("退出程序！\n");
        break;
      default:
        printf("选择输入有误！\n");
        break;
    }
    calc_rank(&score);
  } while (choice != 0);
  return 0;
}

这是一个简单的实现，实际应用中可能需要更多的功能和更完善的实现。