Thread: File Handling Problem

Hi All,

I'm trying to process a text file. My file has a line format like the following:

'some text' bnm 'some numbers'

This line format repeats itself until the end of the text. The thing I need is 'some numbers'.

What I want to do is:
- scan every line for bnm
- when I find bnm, I want to read 'some numbers' after the bnm and write them to another file in the same order.
- this will go on like this until the end of the file.

I tried really hard, but I couldn't do it. I need some advice about which i/o function to use, some kind of algorithm perhaps. Any idea?

No, 'bnm' is unique. The part of the line I'm interested in is actually like this:

...\tN 4021.156431\t\t\t\tE 2945.142006 and continues

('\t' stands for horizontal tab)

I want to take out the numbers from the file. Algorithmically I can say, when I meet '\tN ', I know that I want the next 11 characters and when I meet '\tE ' again 11 characters after that should be read and written somewhere else.

Prelude, thanks for your example, it will be helpful for me.

Originally Posted by Prelude

Does the 'some text' potentially contain bnm? If not then it's really a simple matter of shifting forward to 'some numbers', since all you're doing is writing everything after bnm to the output file:

Code:

while ( fgets ( line, sizeof line, in ) != NULL ) {
  char *p = strstr ( line, "bnm" );

  if ( p == NULL )
    panic();

  while ( isspace ( *p ) )
    ++p;

  fputs ( p, out );
}

You'd want to increment p by 3 (strlen("bnm")) before the while, otherwise p will be pointing to the 'b' character in "bnm", and the isspace(*p) will immediately fail, rendering the while ( isspace... ) pointless.