CodeAlpha_BankingSystem.c

/*
 * ============================================================
 *   BANK ACCOUNT MANAGEMENT SYSTEM
 *   Language : C
 *   Features : Deposit | Withdraw | Balance Enquiry | Exit
 *   Storage  : File Handling (accounts.dat)
 * ============================================================
 */

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

/* ─── Data Structure ─────────────────────────────────────── */
typedef struct {
    int    accNumber;
    char   name[50];
    float  balance;
} Account;

/* ─── File name constant ─────────────────────────────────── */
#define FILE_NAME "accounts.dat"

/* ─── Function Prototypes ────────────────────────────────── */
void   createAccount();
void   deposit();
void   withdraw();
void   balanceEnquiry();
void   listAllAccounts();
int    findAccount(int accNo, Account *acc);
void   updateAccount(Account acc);
void   displayMenu();
void   clearScreen();
void   printBanner();
void   printDivider();

/* ══════════════════════════════════════════════════════════
   MAIN
   ══════════════════════════════════════════════════════════ */
int main() {
    int choice;

    printBanner();

    while (1) {
        displayMenu();
        printf("  Enter your choice : ");
        if (scanf("%d", &choice) != 1) {
            /* flush bad input */
            while (getchar() != '\n');
            printf("\n  [!] Invalid input. Please enter a number.\n");
            continue;
        }

        switch (choice) {
            case 1: createAccount();    break;
            case 2: deposit();          break;
            case 3: withdraw();         break;
            case 4: balanceEnquiry();   break;
            case 5: listAllAccounts();  break;
            case 6:
                printf("\n  Thank you for using the Bank System. Goodbye!\n\n");
                exit(0);
            default:
                printf("\n  [!] Invalid choice. Please try again.\n");
        }
    }
    return 0;
}

/* ══════════════════════════════════════════════════════════
   DISPLAY MENU
   ══════════════════════════════════════════════════════════ */
void displayMenu() {
    printDivider();
    printf("         MAIN MENU\n");
    printDivider();
    printf("  1. Create New Account\n");
    printf("  2. Deposit Money\n");
    printf("  3. Withdraw Money\n");
    printf("  4. Balance Enquiry\n");
    printf("  5. List All Accounts\n");
    printf("  6. Exit\n");
    printDivider();
}

/* ══════════════════════════════════════════════════════════
   CREATE ACCOUNT
   ══════════════════════════════════════════════════════════ */
void createAccount() {
    Account acc;
    FILE   *fp;

    printDivider();
    printf("         CREATE NEW ACCOUNT\n");
    printDivider();

    printf("  Enter Account Number  : ");
    scanf("%d", &acc.accNumber);

    /* Check for duplicate */
    Account temp;
    if (findAccount(acc.accNumber, &temp)) {
        printf("\n  [!] Account %d already exists!\n", acc.accNumber);
        return;
    }

    printf("  Enter Account Holder  : ");
    getchar();   /* flush newline */
    fgets(acc.name, sizeof(acc.name), stdin);
    acc.name[strcspn(acc.name, "\n")] = '\0';   /* strip newline */

    printf("  Enter Initial Deposit : Rs. ");
    scanf("%f", &acc.balance);

    if (acc.balance < 0) {
        printf("\n  [!] Initial deposit cannot be negative.\n");
        return;
    }

    fp = fopen(FILE_NAME, "ab");
    if (!fp) {
        printf("\n  [!] Error opening file.\n");
        return;
    }
    fwrite(&acc, sizeof(Account), 1, fp);
    fclose(fp);

    printf("\n  [✔] Account created successfully!\n");
    printf("  Account No : %d | Name : %s | Balance : Rs. %.2f\n",
           acc.accNumber, acc.name, acc.balance);
}

/* ══════════════════════════════════════════════════════════
   DEPOSIT
   ══════════════════════════════════════════════════════════ */
void deposit() {
    int   accNo;
    float amount;
    Account acc;

    printDivider();
    printf("         DEPOSIT MONEY\n");
    printDivider();

    printf("  Enter Account Number : ");
    scanf("%d", &accNo);

    if (!findAccount(accNo, &acc)) {
        printf("\n  [!] Account not found.\n");
        return;
    }

    printf("  Current Balance      : Rs. %.2f\n", acc.balance);
    printf("  Enter Deposit Amount : Rs. ");
    scanf("%f", &amount);

    if (amount <= 0) {
        printf("\n  [!] Deposit amount must be positive.\n");
        return;
    }

    acc.balance += amount;
    updateAccount(acc);

    printf("\n  [✔] Rs. %.2f deposited successfully.\n", amount);
    printf("  New Balance          : Rs. %.2f\n", acc.balance);
}

/* ══════════════════════════════════════════════════════════
   WITHDRAW
   ══════════════════════════════════════════════════════════ */
void withdraw() {
    int   accNo;
    float amount;
    Account acc;

    printDivider();
    printf("         WITHDRAW MONEY\n");
    printDivider();

    printf("  Enter Account Number  : ");
    scanf("%d", &accNo);

    if (!findAccount(accNo, &acc)) {
        printf("\n  [!] Account not found.\n");
        return;
    }

    printf("  Current Balance       : Rs. %.2f\n", acc.balance);
    printf("  Enter Withdraw Amount : Rs. ");
    scanf("%f", &amount);

    if (amount <= 0) {
        printf("\n  [!] Withdrawal amount must be positive.\n");
        return;
    }

    if (amount > acc.balance) {
        printf("\n  [!] Insufficient funds! Available: Rs. %.2f\n", acc.balance);
        return;
    }

    acc.balance -= amount;
    updateAccount(acc);

    printf("\n  [✔] Rs. %.2f withdrawn successfully.\n", amount);
    printf("  Remaining Balance     : Rs. %.2f\n", acc.balance);
}

/* ══════════════════════════════════════════════════════════
   BALANCE ENQUIRY
   ══════════════════════════════════════════════════════════ */
void balanceEnquiry() {
    int accNo;
    Account acc;

    printDivider();
    printf("         BALANCE ENQUIRY\n");
    printDivider();

    printf("  Enter Account Number : ");
    scanf("%d", &accNo);

    if (!findAccount(accNo, &acc)) {
        printf("\n  [!] Account not found.\n");
        return;
    }

    printf("\n  ┌─────────────────────────────────────┐\n");
    printf("  │  Account No  : %-20d   │\n", acc.accNumber);
    printf("  │  Name        : %-20s   │\n", acc.name);
    printf("  │  Balance     : Rs. %-16.2f   │\n", acc.balance);
    printf("  └─────────────────────────────────────┘\n");
}

/* ══════════════════════════════════════════════════════════
   LIST ALL ACCOUNTS
   ══════════════════════════════════════════════════════════ */
void listAllAccounts() {
    Account acc;
    FILE   *fp;
    int     count = 0;

    printDivider();
    printf("         ALL ACCOUNTS\n");
    printDivider();
    printf("  %-10s  %-25s  %s\n", "Acc. No", "Account Holder", "Balance (Rs.)");
    printDivider();

    fp = fopen(FILE_NAME, "rb");
    if (!fp) {
        printf("  No accounts found.\n");
        return;
    }

    while (fread(&acc, sizeof(Account), 1, fp) == 1) {
        printf("  %-10d  %-25s  %.2f\n", acc.accNumber, acc.name, acc.balance);
        count++;
    }
    fclose(fp);

    printDivider();
    if (count == 0)
        printf("  No accounts found.\n");
    else
        printf("  Total Accounts : %d\n", count);
}

/* ══════════════════════════════════════════════════════════
   HELPER : Find Account by Number
   Returns 1 if found, 0 otherwise. Fills *acc.
   ══════════════════════════════════════════════════════════ */
int findAccount(int accNo, Account *acc) {
    FILE *fp = fopen(FILE_NAME, "rb");
    if (!fp) return 0;

    while (fread(acc, sizeof(Account), 1, fp) == 1) {
        if (acc->accNumber == accNo) {
            fclose(fp);
            return 1;
        }
    }
    fclose(fp);
    return 0;
}

/* ══════════════════════════════════════════════════════════
   HELPER : Update an Existing Account Record in File
   ══════════════════════════════════════════════════════════ */
void updateAccount(Account updated) {
    FILE   *fp, *temp;
    Account acc;

    fp   = fopen(FILE_NAME, "rb");
    temp = fopen("temp.dat",  "wb");

    if (!fp || !temp) {
        printf("\n  [!] File error during update.\n");
        return;
    }

    while (fread(&acc, sizeof(Account), 1, fp) == 1) {
        if (acc.accNumber == updated.accNumber)
            fwrite(&updated, sizeof(Account), 1, temp);
        else
            fwrite(&acc, sizeof(Account), 1, temp);
    }

    fclose(fp);
    fclose(temp);

    remove(FILE_NAME);
    rename("temp.dat", FILE_NAME);
}

/* ══════════════════════════════════════════════════════════
   UI HELPERS
   ══════════════════════════════════════════════════════════ */
void printBanner() {
    printf("\n");
    printf("  ╔══════════════════════════════════════════╗\n");
    printf("  ║   BANK ACCOUNT MANAGEMENT SYSTEM  v1.0   ║\n");
    printf("  ║          Built in C  |  File-Based       ║\n");
    printf("  ╚══════════════════════════════════════════╝\n\n");
}

void printDivider() {
    printf("  ------------------------------------------\n");
}