School Billing System in C

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

// Structure to represent student information
struct Student {
    int rollNumber;
    char name[100];
    double feesPaid;
    double totalFees;
};

// Function to create a new student record
void createStudent() {
    struct Student newStudent;
    printf("Enter Roll Number: ");
    scanf("%d", &newStudent.rollNumber);
    printf("Enter Name: ");
    scanf("%s", newStudent.name);
    printf("Enter Total Fees: ");
    scanf("%lf", &newStudent.totalFees);
    newStudent.feesPaid = 0;

    FILE *file = fopen("students.txt", "a");
    if (file == NULL) {
        perror("Error opening file");
        exit(1);
    }

    fprintf(file, "%d %s %.2lf %.2lf\n", newStudent.rollNumber, newStudent.name, newStudent.totalFees, newStudent.feesPaid);
    fclose(file);

    printf("Student record created successfully.\n");
}

// Function to update fees payment for a student
void updateFees() {
    int rollNumber;
    double paymentAmount;

    printf("Enter Roll Number: ");
    scanf("%d", &rollNumber);
    printf("Enter Payment Amount: ");
    scanf("%lf", &paymentAmount);

    FILE *file = fopen("students.txt", "r+");
    if (file == NULL) {
        perror("Error opening file");
        exit(1);
    }

    struct Student student;
    int found = 0;

    while (fscanf(file, "%d %s %lf %lf", &student.rollNumber, student.name, &student.totalFees, &student.feesPaid) != EOF) {
        if (student.rollNumber == rollNumber) {
            if (student.feesPaid + paymentAmount <= student.totalFees) {
                student.feesPaid += paymentAmount;
                fseek(file, -sizeof(student), SEEK_CUR);
                fprintf(file, "%d %s %.2lf %.2lf", student.rollNumber, student.name, student.totalFees, student.feesPaid);
                found = 1;
                break;
            } else {
                printf("Payment amount exceeds total fees.\n");
                found = 1;
                break;
            }
        }
    }

    fclose(file);

    if (found) {
        printf("Payment updated successfully.\n");
    } else {
        printf("Student not found.\n");
    }
}

// Function to generate a bill for a student
void generateBill() {
    int rollNumber;

    printf("Enter Roll Number: ");
    scanf("%d", &rollNumber);

    FILE *file = fopen("students.txt", "r");
    if (file == NULL) {
        perror("Error opening file");
        exit(1);
    }

    struct Student student;
    int found = 0;

    while (fscanf(file, "%d %s %lf %lf", &student.rollNumber, student.name, &student.totalFees, &student.feesPaid) != EOF) {
        if (student.rollNumber == rollNumber) {
            double remainingFees = student.totalFees - student.feesPaid;
            printf("Student Name: %s\n", student.name);
            printf("Total Fees: %.2lf\n", student.totalFees);
            printf("Fees Paid: %.2lf\n", student.feesPaid);
            printf("Remaining Fees: %.2lf\n", remainingFees);
            found = 1;
            break;
        }
    }

    fclose(file);

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

int main() {
    int choice;

    while (1) {
        printf("\nSchool Billing System Menu:\n");
        printf("1. Create Student Record\n");
        printf("2. Update Fees Payment\n");
        printf("3. Generate Bill\n");
        printf("4. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                createStudent();
                break;
            case 2:
                updateFees();
                break;
            case 3:
                generateBill();
                break;
            case 4:
                exit(0);
            default:
                printf("Invalid choice. Please try again.\n");
        }
    }

    return 0;
}