/* Program to list a text file to the screen, with line numbers. */

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

main () {
    FILE * fin;
    char fname[81];
    int ch, previous_ch, line_num = 1;

    printf("Enter name of file to read: ");
    scanf("%80s", fname);

    fin = fopen(fname, "r");
    if (fin == NULL) {
        fprintf(stderr, "File cannot be opened.\n");
        exit(1);
    }

    /* Method: generate a line number when the previous character is '\n' */
    previous_ch = '\n';
    while ((ch = getc(fin)) >= 0) {   /* while not eof */
        if (previous_ch == '\n') {    /* Start of a line? */
            fprintf(stderr, "%4d  ", line_num);
            line_num++;
        }
        putc(ch, stderr);
        previous_ch = ch;
    }

    fclose(fin);
}