carriage return by fgets

Question

I am running the following code:

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

int main(){
    FILE *fp;
    if((fp=fopen("test.txt","r"))==NULL){
        printf("File can't be read\n");
        exit(1);
    }
    char str[50];
    fgets(str,50,fp);
    printf("%s",str);
    return 0;
}

text.txt contains: I am a boy\r\n

Since I am on Windows, it takes \r\n as a new line character and so if I read this from a file it should store "I am a boy\n\0" in str, but I get "I am a boy\r\n". I am using mingw compiler.

Answer 1

The behavior depends on the c library implementation and which mode you pass to fopen. See this quote from the MSDN documentation on fopen (fopen on MSDN):

b - Open in binary (untranslated) mode; translations involving carriage-return and linefeed characters are suppressed.

Means, if you use the Microsoft c library, and open your file omitting the 'b', the carriage return characters will be removed from the stream.

Since you're using mingw, your compiler probably links against the GNU c library which follows the POSIX standard. This is what the GNU documentation says about fopen (fopen on gnu.org):

The character ‘b’ in opentype has a standard meaning; it requests a binary stream rather than a text stream. But this makes no difference in POSIX systems (including GNU systems).

Concluding: you're omitting the 'b' mode char, which opens your stream in text mode. You're on Windows but use a GNU c library which makes no difference between text and binary mode. This is why fgets reads both carriage return and new line.