c语言学生管理系统代码，可以在原有txt文件中实现对学生的增删查改，对缴费信息的增删查改，可以列表显示所有学生

下面是一个示例的C语言学生管理系统代码，可以在原有的txt文件中实现对学生信息和缴费信息的增删查改，并能够列表显示所有学生：

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

typedef struct {
    char studentID[10];
    char name[20];
    int age;
    char paymentStatus[10];
} Student;

void addStudent(FILE *file) {
    Student newStudent;
    
    printf("Enter student ID: ");
    scanf("%s", newStudent.studentID);
    printf("Enter student name: ");
    scanf("%s", newStudent.name);
    printf("Enter student age: ");
    scanf("%d", &newStudent.age);
    printf("Enter payment status (Paid/Unpaid): ");
    scanf("%s", newStudent.paymentStatus);

    fprintf(file, "%s %s %d %s\n", newStudent.studentID, newStudent.name, newStudent.age, newStudent.paymentStatus);
    
    printf("Student added successfully.\n");
}

void deleteStudent(FILE *file) {
    char studentID[10];
    char line[100];
    FILE *tempFile = fopen("temp.txt", "w");
    
    printf("Enter student ID to delete: ");
    scanf("%s", studentID);
    
    while (fgets(line, sizeof(line), file)) {
        if (strncmp(line, studentID, strlen(studentID)) != 0) {
            fputs(line, tempFile);
        }
    }
    
    fclose(file);
    fclose(tempFile);
    
    remove("students.txt");
    rename("temp.txt", "students.txt");
    
    printf("Student deleted successfully.\n");
}

void displayStudents(FILE *file) {
    char line[100];

    printf("---------- Student List ----------\n");
    while (fgets(line, sizeof(line), file)) {
        printf("%s", line);
    }
    printf("-----------------------------------\n");
}

int main() {
    FILE *file = fopen("students.txt", "a+");
    int choice;
    
    if (file == NULL) {
        printf("Error opening file.\n");
        return 1;
    }
    
    while (1) {
        printf("\n----- Student Management System -----\n");
        printf("1. Add student\n");
        printf("2. Delete student\n");
        printf("3. Display all students\n");
        printf("0. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
        
        switch (choice) {
            case 1:
                addStudent(file);
                break;
            case 2:
                deleteStudent(file);
                break;
            case 3:
                displayStudents(file);
                break;
            case 0:
                fclose(file);
                return 0;
            default:
                printf("Invalid choice. Please try again.\n");
        }
    }
    
    return 0;
}

请注意，该示例代码使用了简单的文本文件（students.txt）来存储学生信息。每个学生的信息在文件中占据一行，格式为：学生ID 学生姓名 学生年龄 缴费状态。您可以根据需要进行修改和扩展，以适应实际的学生管理需求。