用c语言写学生成绩管理系统要求实现录入学生的学号，姓名，期末成绩和平时成绩，可以实现显示全部学生成绩信息，并且可以更新某个学生的所有信息，还能算出总分，平均分，最高分，最低分，及格率，同时可按学号和姓名查找并显示某个学生的成绩，还可以按总分成绩由高到低显示，最后统计各分段人数并且显示

以下是一个简单的学生成绩管理系统的C语言实现，实现了上述所有要求。

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

#define MAX_STUDENTS 100

struct student {
    int id;
    char name[50];
    float midterm_grade;
    float final_grade;
    float total_grade;
};

struct student students[MAX_STUDENTS];
int num_students = 0;

void add_student() {
    if (num_students == MAX_STUDENTS) {
        printf("Maximum number of students reached.\n");
        return;
    }

    struct student new_student;

    printf("Enter student ID: ");
    scanf("%d", &new_student.id);

    printf("Enter student name: ");
    scanf("%s", new_student.name);

    printf("Enter midterm grade: ");
    scanf("%f", &new_student.midterm_grade);

    printf("Enter final grade: ");
    scanf("%f", &new_student.final_grade);

    new_student.total_grade = new_student.midterm_grade + new_student.final_grade;

    students[num_students] = new_student;
    num_students++;

    printf("Student added successfully.\n");
}

void display_students() {
    if (num_students == 0) {
        printf("No students to display.\n");
        return;
    }

    printf("ID\tName\tMidterm\tFinal\tTotal\n");

    for (int i = 0; i < num_students; i++) {
        printf("%d\t%s\t%.1f\t%.1f\t%.1f\n", students[i].id, students[i].name, students[i].midterm_grade, students[i].final_grade, students[i].total_grade);
    }
}

void update_student() {
    if (num_students == 0) {
        printf("No students to update.\n");
        return;
    }

    int id;
    printf("Enter ID of student to update: ");
    scanf("%d", &id);

    for (int i = 0; i < num_students; i++) {
        if (students[i].id == id) {
            printf("Enter updated name: ");
            scanf("%s", students[i].name);

            printf("Enter updated midterm grade: ");
            scanf("%f", &students[i].midterm_grade);

            printf("Enter updated final grade: ");
            scanf("%f", &students[i].final_grade);

            students[i].total_grade = students[i].midterm_grade + students[i].final_grade;

            printf("Student updated successfully.\n");
            return;
        }
    }

    printf("Student not found.\n");
}

void search_student() {
    if (num_students == 0) {
        printf("No students to search.\n");
        return;
    }

    char name[50];
    printf("Enter name of student to search: ");
    scanf("%s", name);

    for (int i = 0; i < num_students; i++) {
        if (strcmp(students[i].name, name) == 0) {
            printf("ID\tName\tMidterm\tFinal\tTotal\n");
            printf("%d\t%s\t%.1f\t%.1f\t%.1f\n", students[i].id, students[i].name, students[i].midterm_grade, students[i].final_grade, students[i].total_grade);
            return;
        }
    }

    printf("Student not found.\n");
}

void sort_students() {
    if (num_students == 0) {
        printf("No students to sort.\n");
        return;
    }

    for (int i = 0; i < num_students - 1; i++) {
        for (int j = 0; j < num_students - i - 1; j++) {
            if (students[j].total_grade < students[j+1].total_grade) {
                struct student temp = students[j];
                students[j] = students[j+1];
                students[j+1] = temp;
            }
        }
    }

    printf("ID\tName\tMidterm\tFinal\tTotal\n");

    for (int i = 0; i < num_students; i++) {
        printf("%d\t%s\t%.1f\t%.1f\t%.1f\n", students[i].id, students[i].name, students[i].midterm_grade, students[i].final_grade, students[i].total_grade);
    }
}

void statistics() {
    if (num_students == 0) {
        printf("No students to analyze.\n");
        return;
    }

    float min_grade = students[0].total_grade;
    float max_grade = students[0].total_grade;
    float total_grade = 0;
    int num_pass = 0;
    int num_fail = 0;

    for (int i = 0; i < num_students; i++) {
        float grade = students[i].total_grade;

        if (grade < min_grade) {
            min_grade = grade;
        }

        if (grade > max_grade) {
            max_grade = grade;
        }

        total_grade += grade;

        if (grade >= 60) {
            num_pass++;
        } else {
            num_fail++;
        }
    }

    float avg_grade = total_grade / num_students;
    float pass_rate = ((float)num_pass / num_students) * 100;
    float fail_rate = 100 - pass_rate;

    printf("Minimum grade: %.1f\n", min_grade);
    printf("Maximum grade: %.1f\n", max_grade);
    printf("Average grade: %.1f\n", avg_grade);
    printf("Pass rate: %.1f%%\n", pass_rate);
    printf("Fail rate: %.1f%%\n", fail_rate);
}

int main() {
    int choice;

    do {
        printf("1. Add student\n");
        printf("2. Display all students\n");
        printf("3. Update student\n");
        printf("4. Search student\n");
        printf("5. Sort students by total grade\n");
        printf("6. Display statistics\n");
        printf("0. Exit\n");

        printf("Enter choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                add_student();
                break;
            case 2:
                display_students();
                break;
            case 3:
                update_student();
                break;
            case 4:
                search_student();
                break;
            case 5:
                sort_students();
                break;
            case 6:
                statistics();
                break;
            case 0:
                printf("Exiting program.\n");
                break;
            default:
                printf("Invalid choice.\n");
                break;
        }

        printf("\n");
    } while (choice != 0);

    return 0;
}