Exercise 7.6 - Compare Two files¶

/* Write a program to compare two files, printing the first line where
 * they differ.
 */

#include <stdio.h>

int main(int argc, char *argv[]) {
    FILE *fp1, *fp2;
    void filecmp(FILE *, FILE *);

    if (argc == 1) {
        /* no args; copy standard input */
        printf("Please provide two files");
        return 1;
    } else
        while (--argc > 0) {
            if ((fp1 = fopen(argv[1], "r")) == NULL) {
                printf("cat: can't open %s\n", *argv);
                return 1;
            }

            if ((fp2 = fopen(argv[2], "r")) == NULL) {
                printf("cat: can't open %s\n", *argv);
                return 1;
            }
            filecmp(fp1, fp2);
            fclose(fp1);
            fclose(fp2);
        }

    return 0;
}

void filecmp(FILE *fp1, FILE *fp2) {
    int f1, f2;
    while (1) {
        if ((f1 = getc(fp1)) == EOF)
            break;
        if ((f2 = getc(fp2)) == EOF)
            break;

        /* TODO: Senthil Print the full sentence */

        if (f1 != f2) {
            putchar(f1);
            putchar(f2);
            break;
        }
    }
}