Why do I get a 'ÿ' char after every include that is extracted by my parser? - C

Question

I have this function:

/*This func runs *.c1 file, and replace every include file with its content
It will save those changes to *.c2 file*/
void includes_ext         


        

Answer 1

You major problem is this loop.

  while (!feof(header_fp)) /*copy header file content to *.c2 file*/
  {
   ch=fgetc(header_fp);
   fputc(ch,c2_fp);
  }/*while(4)*/

When fgetc encounters the end of file, it will return EOF, which is a negative integer. You store this in a char and then without checking write it out to the other file.

feof is very rarely useful as a loop condition. Most of the time it is better to check the return value of a read function.

You should always store to return value of fgetc in an int so that you can check the return value for errors (either an end-of-file condition or some other error). fputc takes in int, in any case.

A better way to construct the loop would be as follows.

int ch_hdr;
while((ch_hdr = fgetc(header_fp)) != EOF)
{
    fputc(ch_hdr, c2_fp);
}

Answer 2

If you look at your code you have to places where you write to the target file.

If I were you I would set a break point at

        }/*frst if*/
        else
        {
        fputc(ch,c2_fp); // brk point here
        }

to check what you are actually writing there.

Answer 3

"ÿ" corresponds to the code point 0xFF. fgetc returns EOF when the end of file is reached, which is (usually) defined as -1. Store -1 in a char and you'll wind up with 0xFF. You must check for EOF between calling fgetc and fpuc.

int ch;
...
/*copy header file content to *.c2 file*/
for (ch=fgetc(header_fp); ch > -1; ch=fgetc(header_fp)) {
   fputc(ch,c2_fp);
}

Instead of getting characters one at a time, you could use fgets to get a block of characters.

#ifndef BUFSIZE
#  define BUFSIZE 1024
#endif
char buf[BUFSIZE], *read;
...
/*copy header file content to *.c2 file*/
while ((read = fgets(buf, BUFSIZE, header_fp))) {
    fputs(buf, c2_fp);
}