luc089.c (3071B)
1 /* 2 * Author : Amit Dutta <amitdutta4255@gmail.com> 3 * Date : 08 Feb 2026 4 * Repo : https://github.com/notamitgamer/bsc 5 * License : MIT License (See the LICENSE file for details) 6 */ 7 8 /* Update 'CUSTOMER.DAT' balance using 'TRANSACTIONS.DAT' (Deposit/Withdrawal). Ensure balance doesn't fall below Rs. 100 on withdrawal. 9 */ 10 /* Let Us C, Chap- 19 (File Input/Output), Qn No.: B(e) */ 11 12 /* This file is auto-generated by a bot. */ 13 /* This code is not compiled; it is for reference only. */ 14 15 16 #include <stdio.h> 17 #include <stdlib.h> 18 #include <string.h> 19 #include <ctype.h> 20 21 struct customer { 22 int accno; 23 char name[30]; 24 float balance; 25 }; 26 27 struct trans { 28 int accno; 29 char trans_type; 30 float amount; 31 }; 32 33 void create_files(); 34 void update_customer(struct customer *c, int n, struct trans t); 35 36 int main() 37 { 38 FILE *fc, *ft; 39 struct customer cust[100]; 40 struct trans t; 41 int i, n_cust = 0; 42 43 create_files(); // Generate dummy data 44 45 // 1. Load all customers into memory 46 fc = fopen("CUSTOMER.DAT", "rb"); 47 if (fc == NULL) exit(1); 48 49 while (fread(&cust[n_cust], sizeof(struct customer), 1, fc) == 1) 50 { 51 n_cust++; 52 } 53 fclose(fc); 54 55 // 2. Process transactions sequentially 56 ft = fopen("TRANSACTIONS.DAT", "rb"); 57 if (ft == NULL) exit(2); 58 59 printf("Processing Transactions...\n"); 60 while (fread(&t, sizeof(struct trans), 1, ft) == 1) 61 { 62 update_customer(cust, n_cust, t); 63 } 64 fclose(ft); 65 66 // 3. Write updated data back to CUSTOMER.DAT 67 fc = fopen("CUSTOMER.DAT", "wb"); 68 fwrite(cust, sizeof(struct customer), n_cust, fc); 69 fclose(fc); 70 71 printf("Update Complete. New Balances:\n"); 72 for(i=0; i<n_cust; i++) 73 printf("%d %s: %.2f\n", cust[i].accno, cust[i].name, cust[i].balance); 74 75 return 0; 76 } 77 78 void update_customer(struct customer *c, int n, struct trans t) 79 { 80 int i; 81 for (i = 0; i < n; i++) 82 { 83 if (c[i].accno == t.accno) 84 { 85 if (t.trans_type == 'D') 86 { 87 c[i].balance += t.amount; 88 printf("Acc %d: Deposited %.2f\n", t.accno, t.amount); 89 } 90 else if (t.trans_type == 'W') 91 { 92 if ((c[i].balance - t.amount) >= 100) 93 { 94 c[i].balance -= t.amount; 95 printf("Acc %d: Withdrew %.2f\n", t.accno, t.amount); 96 } 97 else 98 { 99 printf("Acc %d: Withdrawal denied (Min bal constraint)\n", t.accno); 100 } 101 } 102 return; 103 } 104 } 105 printf("Transaction Error: Acc %d not found\n", t.accno); 106 } 107 108 void create_files() 109 { 110 struct customer c[] = {{101, "A", 500}, {102, "B", 1000}, {103, "C", 200}}; 111 struct trans t[] = {{101, 'D', 200}, {102, 'W', 500}, {103, 'W', 150}}; // 103 fail 112 FILE *f1 = fopen("CUSTOMER.DAT", "wb"); 113 FILE *f2 = fopen("TRANSACTIONS.DAT", "wb"); 114 fwrite(c, sizeof(struct customer), 3, f1); 115 fwrite(t, sizeof(struct trans), 3, f2); 116 fclose(f1); fclose(f2); 117 }