Thread: The content read from txt file is followed by a square, when using fgets() function.

Dear all,

In my app, I used fgets(_Name, 30, fp_t) to read a string (for instance either "NAME_ID", "A DOG" or whatever that is not specific) from a txt file and save the value to a string pointer _Name. I.e. _Name is the string pointer of which value is "NAME_ID_Square" after reading. _Square means there is a square following NAME_ID, which is shown in the debug windows in VS2005. However, this leads strcmp("NAME_ID", "NAME_ID_SQUARE") returns none-zero values, while it ought to be the same in the scenario.

Therefore, do you have any idea about the problem? And how shall I remove the square in the pointer of which value is "NAME_ID_Square"?

Thanks in advance,

Regards,

Qing

> I think fgets leaves in \r\n.
If you open the file in text mode, then the OS line ending should be converted into just \n (independent of the host OS).

If you try to read a text file opened in binary mode, then you don't get this translation happening.

Originally Posted by 39ster

Try trim the line like this:

Code:

size_t nameLen = strlen(_Name);

while(nameLen)
{
  if(_Name[nameLen-1] < ' ')
    _Name[--nameLen] = 0;
  else break;
}

I think fgets leaves in \r\n. That should remove anything with an ascii value < then the space bar from the end of the line.

This is not the most portable code, seeing as there's no guarnatee everything lower than ' ' is a non-visuable character.
For the record, I believe '\r' is 0xA (10) and '\n' is 0xD (13).

Yes that's correct. It should be

Code:

size_t nameLen = strlen(_Name);

while(nameLen)
{
  if(!isprint(_Name[nameLen-1]))
    _Name[--nameLen] = 0;
  else break;
}

Originally Posted by Elysia

For the record, I believe '\r' is 0xA (10) and '\n' is 0xD (13).

I believe it's the other way around.

I can't check right now, but I believe '\n' is 13, if I don't remember wrong. Not sure, though.

http://www.asciitable.com/

Code:

#include <stdio.h>

int main(void)
{
	printf("'\\r' = &#37;d\n'\\n' = %d\n\n", '\r', '\n');
	return 0;
}

Output:

Code:

'\r' = 13
'\n' = 10

I can't check right now, but I believe '\n' is 13, if I don't remember wrong. Not sure, though.

\n is 10 and \r is 13.