How to remove \n of fgets function, without using string functions

Question

Is there a way to remove the \N character from the end of the string reading with fgets, without using string processing functions (strlen, strtok, strcspn, etc) ? I tried that, but it doesn't work

char* remove_newline_char(char *str){
    for(int i = 0; i < str[i]; i++){
        if(str[i] == '\n'){
            str[i] = '\0';
        }
    }
    return str;
}

Please explain the condition `i < str[i]` to yout [rubber duck](https://en.wikipedia.org/wiki/Rubber_duck_debugging). — Some programmer dude, May 09 '22 at 06:50
@Someprogrammerdude ahhhhhh, I just realized what I did ..., thanks — kammy, May 09 '22 at 06:56
@Someprogrammerdude Of course it had to be that way int i = 0; str[i]; i++ — kammy, May 09 '22 at 06:57
Don't add "fixed" to the title. Instead press the checkmark next to the best answer below, or, if there's no good answer, post your own and mark it. — HolyBlackCat, May 09 '22 at 07:03
https://stackoverflow.com/questions/2693776/removing-trailing-newline-character-from-fgets-input — Gerhard, May 09 '22 at 07:05

Clifford · Accepted Answer · 2022-05-09T08:54:52.910

Your code is semantically incorrect. the loop termination expression i < str[i] says:

is the string index less than the character value at that index?

which is of course nonsense - the index and the character value are unrelated.

char* remove_newline_char(char* str)
{
    int i = 0 ;
    while( str[i] != 0 && str[i] != '\n' )
    {
        i++ ;
    }
    str[i] = 0 ;

    return str ;
}

Given that this processing is specific to buffers populated by fgets() rather then a generic string function, there may be merit in combining the input with the processing so that it will not be applied to inappropriate strings (i.e. not from fgets()):

char* freadline( char* str, int num, FILE* stream )
{
    char* ret = NULL ;

    if( (ret = fgets( str, num, str )) != NULL )
    {
        int i = 0 ;
        while( str[i] != 0 && str[i] != '\n' )
        {
            i++ ;
        }
        str[i] = 0 ;
     }
     return ret ;
}

Darth-CodeX · Answer 2 · 2022-05-09T07:34:35.667

You don't need to transverse through the full array and check for each character at every iteration.

As, you have stated don't use string functions, I'm not using strlen() function.

In fgets() newline character is present at length - 1 position.

char* remove_newline_char(char *str){
    size_t len = 0;
    while (str[len])
        len++;
    if(str[len - 1] == '\n')
        str[len - 1] = 0;
    return str;
}

Also, if you know the length of string, then you can avoid that while loop

char* remove_newline_char(char *str, size_t len){
    if(str[len - 1] == '\n')
        str[len - 1] = 0;
    return str;
}

score -1 · Answer 3 · answered May 09 '22 at 07:06

-1

Of course my loop was wrong. Here's the version that works

char* remove_newline_char(char *str){
for(int i = 0; str[i]; i++){
    if(str[i] == '\n'){
        str[i] = '\0';
    }
}
return str;

}

answered May 09 '22 at 07:06

kammy

93
8

5

If you fix it that way, you are running to the end of the original string when you only need to run until `\n` - a minor issue in the case of `fgets()` populated strings perhaps, but your function could be presented with strings not from `fgets()`. – Clifford May 09 '22 at 07:08

How to remove \n of fgets function, without using string functions

3 Answers3