Re: Implementing a file counter (like "ls | wc")

[Holger Kiehl <Holger.Kiehl@dwd.de>]

On Wed, 7 Apr 2004, Luciano Moreira - igLnx wrote:

> -------------- THE CODE HAVE THIS STRUCTURE:
> while ((pFile=readdir(pDir))!=NULL) {
>      sprintf(szBuf, "%s/%s", pPath, pFile->d_name);
>      stat(szBuf, &statFile);
>      if (S_ISDIR(statFile.st_mode))  /// LOOK THAT: We don't use recursive
> searching, we count only files at current directory excluding others
> directories.
>         continue;
> 
>      /* Filtering */
>      if (nNeedFilter) {
>          //// I DONT HAVE THE CODE OF FILTERING NOW
>          //// BUT I CAN SEND IT LATER IF NECESSARY
>         }
> 
>   }
> -------------- CODE FINISH HERE
> 
Don't use sprintf(), its very expansive. Before the while loop put a pointer
after path and / and then strcpy(ptr, pFile->d_name)

stat() is _very_ epansive! It means physical IO and fills up a structure
with things you just don't need. If you really do need to filter out
directories from your result do the stat after it has passed the filter.

> Does have another mechanism to filter without using of strcmp() / memcmp() ?
> How if we dont know the size of extension (.c, .cpp, .teste, .longextension,
> and so on). ?
> 
Compare them yourself with a pointer byte for byte. But the speed gain
will not be so high as when you leave away the stat() call.

Holger