luc093.c - bsc - Comprehensive codebase and cou...

luc093.c (3556B)
      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 Master file (Roll, Name) using Transaction file (Roll, Code Add/Delete). Both files are sorted by Roll.
      9 */
     10 /* Let Us C, Chap- 19 (File Input/Output), Qn No.: B(i) */
     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 student {
     22     int roll;
     23     char name[30];
     24 };
     25 
     26 struct trans {
     27     int roll;
     28     char code; // 'A' for Add, 'D' for Delete
     29     char name[30]; // Only needed for Add
     30 };
     31 
     32 void create_files();
     33 
     34 int main()
     35 {
     36     FILE *fm, *ft, *fn;
     37     struct student m;
     38     struct trans t;
     39     int has_m, has_t;
     40 
     41     create_files();
     42 
     43     fm = fopen("MASTER.DAT", "rb");
     44     ft = fopen("TRANS_ROLL.DAT", "rb");
     45     fn = fopen("NEW_MASTER.DAT", "wb");
     46 
     47     if (!fm || !ft || !fn) exit(1);
     48 
     49     has_m = fread(&m, sizeof(struct student), 1, fm);
     50     has_t = fread(&t, sizeof(struct trans), 1, ft);
     51 
     52     printf("Merging Master and Transaction files...\n");
     53 
     54     while (has_m && has_t)
     55     {
     56         if (m.roll < t.roll)
     57         {
     58             // No transaction for this master record, keep it
     59             fwrite(&m, sizeof(struct student), 1, fn);
     60             has_m = fread(&m, sizeof(struct student), 1, fm);
     61         }
     62         else if (m.roll == t.roll)
     63         {
     64             // Transaction affects this record
     65             if (t.code == 'D')
     66             {
     67                 printf("Deleting Roll %d\n", m.roll);
     68                 // Skip writing 'm' to file (Deleting)
     69                 has_m = fread(&m, sizeof(struct student), 1, fm);
     70             }
     71             else
     72             {
     73                 // Logic error: Can't ADD if ID exists. Maybe Update?
     74                 // Assuming replace or skip. Let's skip T and keep M for now.
     75                 has_m = fread(&m, sizeof(struct student), 1, fm);
     76             }
     77             has_t = fread(&t, sizeof(struct trans), 1, ft);
     78         }
     79         else // m.roll > t.roll
     80         {
     81             // Transaction ID is new
     82             if (t.code == 'A')
     83             {
     84                 struct student new_s;
     85                 new_s.roll = t.roll;
     86                 strcpy(new_s.name, t.name);
     87                 fwrite(&new_s, sizeof(struct student), 1, fn);
     88                 printf("Adding Roll %d\n", new_s.roll);
     89             }
     90             has_t = fread(&t, sizeof(struct trans), 1, ft);
     91         }
     92     }
     93 
     94     // Process remaining Master
     95     while (has_m)
     96     {
     97         fwrite(&m, sizeof(struct student), 1, fn);
     98         has_m = fread(&m, sizeof(struct student), 1, fm);
     99     }
    100 
    101     // Process remaining Transactions (Only Adds)
    102     while (has_t)
    103     {
    104         if (t.code == 'A')
    105         {
    106             struct student new_s = {t.roll, ""};
    107             strcpy(new_s.name, t.name);
    108             fwrite(&new_s, sizeof(struct student), 1, fn);
    109             printf("Adding Roll %d\n", new_s.roll);
    110         }
    111         has_t = fread(&t, sizeof(struct trans), 1, ft);
    112     }
    113 
    114     fclose(fm); fclose(ft); fclose(fn);
    115     return 0;
    116 }
    117 
    118 void create_files()
    119 {
    120     struct student m[] = {{10, "A"}, {20, "B"}, {30, "C"}};
    121     struct trans t[] = {{15, 'A', "NewGuy"}, {20, 'D', ""}, {40, 'A', "LastGuy"}};
    122     
    123     FILE *f1 = fopen("MASTER.DAT", "wb");
    124     fwrite(m, sizeof(struct student), 3, f1);
    125     fclose(f1);
    126 
    127     FILE *f2 = fopen("TRANS_ROLL.DAT", "wb");
    128     fwrite(t, sizeof(struct trans), 3, f2);
    129     fclose(f2);
    130 }
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