Thread: fgets new line at end

Code:

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

#define MAX_COL 70
#define MAX_ROW 20


int main(void) {
    FILE *fp;
    char *text;
    char line[MAX_COL];
    int i;
    
    fp = fopen("input.txt", "r");
    if (fp == NULL) {
        fprintf(stderr, "!!! Failed to open file\n");
        abort();
    }
    
    text = malloc(MAX_COL*MAX_ROW*sizeof(char));
    
    for (i=0; i<MAX_ROW; i++) {
        if ((fgets(line, MAX_COL, fp)) != NULL)
            strcat(text, line);
    }
    
    printf("%s", text);

    return EXIT_SUCCESS;
}

With my input.txt file being

Code:

abcd
efgh

And in particular, there is no new line after the letter h, but when I print out the text string, I get a new line after h. Why is this?

Are you *sure* there's no new line after the letter h? Just because there's no text on the next line doesn't mean the file doesn't end with a new-line character.

Your editor is probably adding it by default. If you're on Linux or the like, that is very probable. Not sure if it's a POSIX standard thing or if the editor is doing it to "be safe" since some programs wont behave so well if it's not there. Try hexdump -C input.txt and look for a 0a byte at the end. Your editor may have an option to disable that feature.

Oh I see. The new line isn't a big deal for me in this case, I was just worried that I was doing something wrong.

Originally Posted by Salem

Don't assume that memory you get from malloc is filled with zeros.
If the first byte isn't \0 when you come to do the strcat calls, you're stuck.

Right, thanks. I'll go ahead and add

Code:

text[0] = '\0'

after I malloc.