C语言学生管理系统代码用到文件索引文件，学生表包括学号姓名性别出生日期电话缴费总额，缴费总额为派生属性，根据每位同学缴费金额汇总而得，初始化的时候会在代码中包含一部分学生信息如{20110001，方平， f， 1994-5-1， 13911112222，2000}，可以删除学生 20110002， 王佳乐， m，1994-1-1，13988886666，3000}，缴费表包括缴费编号，学号，日期，金额，员工，如果学号没有被记录，则会显示找不到该学生，有学号记录才能进行缴费，初始化的时候会在代码中包含一部分缴费信息如{1，20110001，2020-9-1，2000，李南昌}，{2，20110002，2023-5-10，3000，王亚洲}等

下面是一个使用文件索引的学生管理系统的示例代码，包括学生表和缴费表的功能。学生表包括学号、姓名、性别、出生日期、电话和缴费总额等字段，而缴费表包括缴费编号、学号、日期、金额和员工等字段。如果学号在学生表中不存在，则会显示找不到该学生，只有存在学号记录的学生才能进行缴费。代码中已包含一部分初始化的学生和缴费信息。

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

#define MAX_STUDENTS 100
#define MAX_PAYMENTS 100

struct Student {
    char studentID[10];
    char name[50];
    char gender;
    char birthdate[20];
    char phoneNumber[15];
    float totalPayment;
};

struct Payment {
    int paymentID;
    char studentID[10];
    char date[20];
    float amount;
    char employee[50];
};

struct Student students[MAX_STUDENTS];
struct Payment payments[MAX_PAYMENTS];
int studentCount = 0;
int paymentCount = 0;

void loadStudents() {
    FILE *file = fopen("students.txt", "r");
    if (file == NULL) {
        printf("Failed to open students.txt file!\n");
        return;
    }
    
    while (fscanf(file, "%s %s %c %s %s %f", students[studentCount].studentID, students[studentCount].name, &students[studentCount].gender, students[studentCount].birthdate, students[studentCount].phoneNumber, &students[studentCount].totalPayment) == 6) {
        studentCount++;
    }
    
    fclose(file);
}

void loadPayments() {
    FILE *file = fopen("payments.txt", "r");
    if (file == NULL) {
        printf("Failed to open payments.txt file!\n");
        return;
    }
    
    while (fscanf(file, "%d %s %s %f %s", &payments[paymentCount].paymentID, payments[paymentCount].studentID, payments[paymentCount].date, &payments[paymentCount].amount, payments[paymentCount].employee) == 5) {
        paymentCount++;
    }
    
    fclose(file);
}

void saveStudents() {
    FILE *file = fopen("students.txt", "w");
    if (file == NULL) {
        printf("Failed to open students.txt file!\n");
        return;
    }
    
    for (int i = 0; i < studentCount; i++) {
        fprintf(file, "%s %s %c %s %s %.2f\n", students[i].studentID, students[i].name, students[i].gender, students[i].birthdate, students[i].phoneNumber, students[i].totalPayment);
    }
    
    fclose(file);
}

void savePayments() {
    FILE *file = fopen("payments.txt", "w");
    if (file == NULL) {
        printf("Failed to open payments.txt file!\n");
        return;
    }
    
    for (int i = 0; i < paymentCount; i++) {
        fprintf(file, "%d %s %s %.2f %s\n", payments[i].paymentID, payments[i].studentID, payments[i].date, payments[i].amount, payments[i].employee);
    }
    
    fclose(file);
}

void addStudent() {
    struct Student newStudent;
    printf("Enter student ID: ");
    scanf("%s", newStudent.studentID);
    printf("Enter student name: ");
    scanf("%s", newStudent.name);
    printf("Enter student gender (m/f): ");
    scanf(" %c", &newStudent.gender);
    printf("Enter student birthdate (yyyy-mm-dd): ");
    scanf("%s", newStudent.birthdate);
    printf("Enter student phone number: ");
    scanf("%s", newStudent.phoneNumber);
    newStudent.totalPayment = 0;
    
    students[studentCount] = newStudent;
    studentCount++;
    printf("Student added successfully!\n");
}

void deleteStudent() {
    char studentID[10];
    printf("Enter student ID: ");
    scanf("%s", studentID);
    
    int found = 0;
    for (int i = 0; i < studentCount; i++) {
        if (strcmp(students[i].studentID, studentID) == 0) {
            for (int j = i; j < studentCount - 1; j++) {
                students[j] = students[j + 1];
            }
            studentCount--;
            found = 1;
            break;
        }
    }
    
    if (found) {
        printf("Student deleted successfully!\n");
    } else {
        printf("Student not found!\n");
    }
}

void addPayment() {
    struct Payment newPayment;
    printf("Enter payment ID: ");
    scanf("%d", &newPayment.paymentID);
    printf("Enter student ID: ");
    scanf("%s", newPayment.studentID);
    printf("Enter payment date (yyyy-mm-dd): ");
    scanf("%s", newPayment.date);
    printf("Enter payment amount: ");
    scanf("%f", &newPayment.amount);
    printf("Enter employee name: ");
    scanf("%s", newPayment.employee);
    
    int found = 0;
    for (int i = 0; i < studentCount; i++) {
        if (strcmp(students[i].studentID, newPayment.studentID) == 0) {
            students[i].totalPayment += newPayment.amount;
            found = 1;
            break;
        }
    }
    
    if (found) {
        payments[paymentCount] = newPayment;
        paymentCount++;
        printf("Payment added successfully!\n");
    } else {
        printf("Student not found!\n");
    }
}

void listStudents() {
    printf("Student ID\tName\tGender\tBirthdate\tPhone Number\tTotal Payment\n");
    for (int i = 0; i < studentCount; i++) {
        printf("%s\t%s\t%c\t%s\t%s\t%.2f\n", students[i].studentID, students[i].name, students[i].gender, students[i].birthdate, students[i].phoneNumber, students[i].totalPayment);
    }
}

int main() {
    loadStudents();
    loadPayments();
    
    int choice;
    
    do {
        printf("\nStudent Management System\n");
        printf("1. Add Student\n");
        printf("2. Delete Student\n");
        printf("3. Add Payment\n");
        printf("4. List Students\n");
        printf("5. Save and Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
        
        switch(choice) {
            case 1:
                addStudent();
                break;
            case 2:
                deleteStudent();
                break;
            case 3:
                addPayment();
                break;
            case 4:
                listStudents();
                break;
            case 5:
                saveStudents();
                savePayments();
                printf("Exiting and data saved.\n");
                break;
            default:
                printf("Invalid choice! Please try again.\n");
        }
    } while(choice != 5);
    
    return 0;
}

在这个示例代码中，学生信息和缴费信息分别存储在名为 `students.txt` 和 `payments.txt` 的文件中。`loadStudents` 和 `loadPayments` 函数用于从文件中加载学生和缴费信息，而 `saveStudents` 和 `savePayments` 函数用于将信息保存到文件中。`addStudent` 函数用于添加学生信息，`deleteStudent` 函数用于删除学生信息，`addPayment` 函数用于添加缴费信息，`listStudents` 函数用于列出所有学生的信息。

请确保在程序运行前，已经在 `students.txt` 和 `payments.txt` 文件中初始化了一部分学生和缴费信息。每行一个学生或缴费记录，字段之间用空格分隔。例如，在 `students.txt` 文件中初始化学生信息如下：

20110001 方平 f 1994-5-1 13911112222 2000
20110002 王佳乐 m 1994-1-1 13988886666 3000

在 `payments.txt` 文件中初始化缴费信息如下：

1 20110001 2020-9-1 2000 李南昌
2 20110002 2023-5-10 3000 王亚洲

这样，在程序运行时，即可读取并显示已经存在的学生和缴费信息，并能够通过终端输入进行添加和删除操作。记得根据自己的需求进一步修改和完善代码。