Thread: merging files into one

you have to check the return value of fopen each and every time...never assume that the file can be opened!

>> if (out_fp = fopen(out_filename, "w") == '\0')

'\0' is used for representing the ASCII value zero and should only be used with text-based processing - for pointers use 0 or NULL.

so you are checking the return value of 'in_fp'? also if the file can't be opened be sure to bypass any calls to fclose on the handle.

Edit: too late, this post was written before I saw the previous post.

See my added stuff...

Originally Posted by mbooka

Hi,

I am trying to copy several rtf files into one rtf file. this is basically what i have done

Code:

char in_filename[MAXPATHLEN];
char out_filename[MAXPATHLEN];
FILE *in_fp, *out_fp;
char line_buffer[80];

//....get the required file name through user input 
// assumed they lead to correct files so the program does not
// crash on incorrect file path

/* Without the added (blue) parentheses, you have a precedence issue, 
    you are assigning out_fp to the comparison result of fopen()'s return and NULL */
if ((out_fp = fopen(out_filename, "w"))  == /* '\0' WRONG */NULL)
/* fopen returns NULL on error, this is not the same as '\0' */
{
    printf("error opening file");
    break;
}
in_fp = fopen(in_filename, "r");
/* check in_fp is not NULL here.  There is no excuse even if you're sure the 
file exists */
while (fgets(line_buffer, 80, in_fp) != NULL)
    fputs(line_buffer, out_fp);
fclose(in_fp);
fclose(out_fp);

but i get a segmentation fault after reading the first line of the file