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File Search Algorithm

Posted on 1998-06-26
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Last Modified: 2010-04-02
Does anyone have a file Search algorithm I could use?  Example, I want to find mspaint.exe....I want to write a piece of code that would search for that file.  Thanks in advance.
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Question by:mrquija
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8 Comments
 
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Expert Comment

by:RONSLOW
ID: 1251441
Under Win32 you call FindFirstFile/FindNextFile .. these return files that match a given spec and sttributes in a given directory.

Search a directory tree by making the function recursive (ie. look for your particular file and if not fount retrieve all directory names and call the search for each of those.)

In Win32 you can also find an executable that is registered by API calls .. but this may not be what you want.

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by:mrquija
ID: 1251442
I need a searching algorithm for DOS based, sorry.
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Expert Comment

by:saneesh100
ID: 1251443
Hello..
 You want the dos one right. U can do it in the following way..

 Have u used findfirst and findnext ..or ucan use dos interrupts..

 start from c:\(root) and search for the file also add the directory names in an array .Got it. When the current is finished take the last one from directory array ( remove it also) add it to current path and re perform search .If one has nothing inside it .just remove one upto a '\'and again add form array.It will work..

 Please note: it will search from the last one >not like dir /s which will starts from first one..

 Good luck.

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LVL 1

Author Comment

by:mrquija
ID: 1251444
haven't used those functions before.  Could you write code to implement?
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Expert Comment

by:moonlight
ID: 1251445
I will give you an algorithm, the functions are for unix,
use functions in the earlier answers for dos:
 for (dp = readdir(d); dp != NULL;dp = readdir (d) )
   {
   filename = dp -> d_name;
   if ( filename[0] == '.' ) continue ;
   cout << filename <<  "\n";
   }

this is only for your help, not an answer
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Accepted Solution

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RONSLOW earned 10 total points
ID: 1251446
something like this should work (haven't compiled or debugged it .. just typed it in)

char* WhereInThisDir(const char* szSpec, const char* szPath) {
      int lSpec,lPath;
    int lSubDirSpec;
    char* szSubDirSpec;
      int lFullSpec;
    char* szFullSpec;
      int lSubDir;
    char* szSubDir;
    struct _finddata_t aFindData;
    long hFileFind;
      char* szWhere;
   
    /* not found yet */
      szWhere = NULL;
   
    lSpec = strlen(szSpec);
    lPath = strlen(szPath);
   
    /* buffer for searching and returning file name */
    lFullSpec = lPath + 1 + lPath;
    szFullSpec = malloc(lFullSpec+1);
    strcpy(szFullSpec,szPath);
    strcat(szFullSpec,'\\');
    strcat(szFullSpec,szSpec);
   
    /* is it here? */
    hFileFind = _findfirst(szSpec, &aFindData );
    if (hFileFind != -1L ) szWhere = szFullSpec;
   
    /* no longer required */
    if (szWhere != szFullSpec) {
          free(szFullSpec);
    } else {
        /* we are returning the allocated string */
        /* caller needs to free it after use */
        /* similar to strdup */
    }
      _findclose(hFileFind);

    /* say where we found it (if at all) */
    return szWhere;
}

char* WhereInSubDir(const char* szSpec, const char* szPath) {
    int lSpec,lPath;
    int lSubDirSpec;
    char* szSubDirSpec;
    struct _finddata_t aFindData;
    long hFileFind;
      char* szWhere;
   
    /* not found yet */
      szWhere = NULL;
   
    lSpec = strlen(szSpec);
    lPath = strlen(szPath);

    /* make subdir spec for filefind */
      lSubDirSpec = lPath + 4;
      szSubDirSpec = malloc(lSubDirSpec+1);
      strcpy(szSubDirSpec,szPath);
      strcat(szSubDirSpec,'\\*.*');
   
    /* find subdirs */
      hFileFind = _findfirst(szSpec, &aFindData );
      if (hFileFind != -1L ) {
          do {
            /* found a szSubDir */
              if (aFindData.attrib & _A_SUBDIR) {
                  int lName;
                  char* szName;
                  int lSubDir;
                  char* szSubDir;
                  char* szWhere;
               
                  szName = aFindData.name;
                  lName = strlen(szName);

                /* make subdir path name */
                  lSubDir = lPath+1+lName;
                  szSubDir = malloc(lSubDir+1);
                  strcpy(szSubDir,szPath);
                  strcat(szSubDir,'\\');
                  strcat(szSubDir,szName);
               
                /* look in subdir tree */
                  szWhere = WhereInTree(szSpec,szSubDir);
               
                /* no longer required */
                  free(szSubDir);
            }
        } while(!szWhere && _findnext(hFileFind, &aFindData) == 0);
    }

    /* no longer required */
      free(szSubDirSpec);
      _findclose(hFileFind);
   
    /* say where we found it */
      return szWhere;
}

char* WhereInTree(const char* szSpec, const char* szPath) {
    /* returns NULL if not found */
    /* otherwise returns allocated string */
    /* caller needs to free the string */
      const char* szWhere;
   
      szWhere = WhereInThisDir(szSpec,szPath);
      if (! szWhere) szWhere = WhereInSubDir(szSpec,szPath);
      return szWhere;
}

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Author Comment

by:mrquija
ID: 1251447
Im not sure if that code is going to compile either.  Seems too complicated for a file search algorithm?!?   But I'll give it a shot.  If anyone has anything SHORTER, it would be appreciated.
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LVL 10

Expert Comment

by:RONSLOW
ID: 1251448
The main reason for the length is the lengths (sic) you have to go to to set up a findfirst/findnext loop .. mostly the string manipulation.

You could used fixed size buffers to make it a bit simpler ,, as long as you make the buffers big enough.

The alrogithm itself is quite simply .. just the details get in the way.

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