Compare Two Files and Report Mismatches

1#include <stdio.h>
2
3int main() {
4    FILE *file1 = fopen("file1.txt", "r");
5    FILE *file2 = fopen("file2.txt", "r");
6    
7    if (!file1 || !file2) {
8        printf("Error opening files!\n");
9        return 1;
10    }
11    
12    int ch1, ch2;
13    int line = 1, col = 0;
14    int differences = 0;
15    
16    while (1) {
17        ch1 = fgetc(file1);
18        ch2 = fgetc(file2);
19        col++;
20        
21        if (ch1 == '\n') {
22            line++;
23            col = 0;
24        }
25        
26        if (ch1 != ch2) {
27            if (ch1 == EOF) {
28                printf("File 1 is shorter\n");
29                break;
30            } else if (ch2 == EOF) {
31                printf("File 2 is shorter\n");
32                break;
33            } else {
34                printf("Mismatch at line %d, col %d: '%c' vs '%c'\n",
35                       line, col, ch1, ch2);
36                differences++;
37            }
38        }
39        
40        if (ch1 == EOF && ch2 == EOF) break;
41    }
42    
43    if (differences == 0) {
44        printf("Files are identical!\n");
45    } else {
46        printf("Total differences: %d\n", differences);
47    }
48    
49    fclose(file1);
50    fclose(file2);
51    
52    return 0;
53}