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

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

[Luciano Moreira - igLnx]

We implemented a program that use "opendir()", "readdir()", and 
"closedir()" to scan a directory and count the files contained into it.

But, it program have taking more time than "ls | wc" to count files.

Does have any other way to count files faster?

PS: Our program needs sometime to filter files by extension (like: *.c, 
*.cpp, and so on. Thus we use strcmp() to compare last letters of both 
strings).

Luciano

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

[Alphex K.]

On Wed, 07 Apr 2004 11:27:02 -0300
Luciano Moreira - igLnx <lucianolnx@ig.com.br> wrote:

> We implemented a program that use "opendir()", "readdir()", and 
> "closedir()" to scan a directory and count the files contained into it.
How U use this functions?
But I'm think that it's not good method
> 
> But, it program have taking more time than "ls | wc" to count files.
> 
> Does have any other way to count files faster?
> 
> PS: Our program needs sometime to filter files by extension (like: *.c, 
> *.cpp, and so on. Thus we use strcmp() to compare last letters of both 
> strings).
If U want a more speed don't use strcmp or strncmp functions.
> 
> Luciano
> 
U use a C++ ? or C ?
> -
> To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
> the body of a message to majordomo@vger.kernel.org
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---===---
Alphex Kaanoken
Senior developer of Crew IT research labs
web: http://crew.org.ru
mailto:Alphex@Crew.Org.RU


---===---
Alphex Kaanoken
Senior developer of Crew IT research labs
web: http://crew.org.ru
mailto:Alphex@Crew.Org.RU

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

[Luciano Moreira - igLnx]

-------------- 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

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). ?

Luciano

Alphex K. wrote:

>On Wed, 07 Apr 2004 11:27:02 -0300
>Luciano Moreira - igLnx <lucianolnx@ig.com.br> wrote:
>
>  
>
>>We implemented a program that use "opendir()", "readdir()", and 
>>"closedir()" to scan a directory and count the files contained into it.
>>    
>>
>How U use this functions?
>But I'm think that it's not good method
>  
>
>>But, it program have taking more time than "ls | wc" to count files.
>>
>>Does have any other way to count files faster?
>>
>>PS: Our program needs sometime to filter files by extension (like: *.c, 
>>*.cpp, and so on. Thus we use strcmp() to compare last letters of both 
>>strings).
>>    
>>
>If U want a more speed don't use strcmp or strncmp functions.
>  
>
>>Luciano
>>
>>    
>>
>U use a C++ ? or C ?
>  
>
>>-
>>To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
>>the body of a message to majordomo@vger.kernel.org
>>More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>    
>>
>
>
>---===---
>Alphex Kaanoken
>Senior developer of Crew IT research labs
>web: http://crew.org.ru
>mailto:Alphex@Crew.Org.RU
>
>
>---===---
>Alphex Kaanoken
>Senior developer of Crew IT research labs
>web: http://crew.org.ru
>mailto:Alphex@Crew.Org.RU
>
>
>  
>

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

[Holger Kiehl]

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

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

[Steven Smith]

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> while ((pFile=readdir(pDir))!=NULL) {
>      sprintf(szBuf, "%s/%s", pPath, pFile->d_name);
>      stat(szBuf, &statFile);
>      if (S_ISDIR(statFile.st_mode))
>         continue;
If the only reason you're statting the files is to check whether
they're directories, then you can save yourself a system call per
file:

while ((pFile=readdir(pDir))!=NULL) {
     if (pFile->d_type == DT_DIR)
        continue;

This'll probably be quite a bit quicker, and may also save you needing
to call sprintf(), which can be somewhat expensive.

Steven Smith.

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