bits and bytes

I will describe in this post three ways to trim a string of given characters…

1. Using custom function for std::string
2. Using CString
3. Using StrTrim shell API function.

Using custom function for std::string

Its bit strange that std::string doesn’t provide a Trim function , but hey since we’ve got head upon our shoulders we’re gonna write one. . Here is a simple function which removes white space before and after a string. We’ll call it Trim!

void Trim( const std::string& StrToTrim, std::string& TrimmedString )
{
  // Find first non whitespace char in StrToTrim
  std::string::size_type First = StrToTrim.find_first_not_of( ' ' );
  // Check whether something went wrong?
  if( First == std::string::npos )
  {
    First = 0;
  }

  // Find last non whitespace char from StrToTrim
  std::string::size_type Last = StrToTrim.find_last_not_of( ' ' );
  // If something didn't go wrong, Last will be recomputed to get real length of substring
  if( Last != std::string::npos )
  {
    Last = ( Last + 1 ) - First;
  }

  // Copy such a string to TrimmedString
  TrimmedString = StrToTrim.substr( First, Last );
}

int main()
{
  std::string StrToTrim = " 32 Nibu babu thomas 2342 2 23 3 ";
  std::string TrimmedString = "On return will hold trimmed string";
  Trim( StrToTrim, TrimmedString );

  return 0;
}
//Output is: 32 Nibu babu thomas 2342 2 23 3

Using CString

Also CString has a Trim function, if you have the liberty to use CString then that’s another option.

Using StrTrim shell API function

Another option is to use StrTrim shell API function. Here is a demo from MSDN.

#include <windows .h>
#include <iostream .h>
#include "Shlwapi.h" 

void main(void)
{
  //String one
  TCHAR buffer[ ] = TEXT("_!ABCDEFG#");
  TCHAR trim[ ] = TEXT("#A!_"); 

  cout << "The string before calling StrTrim: ";
  cout << buffer;
  cout << "\n"; 

  StrTrim(buffer, trim); 

  cout << "The string after calling StrTrim: ";
  cout << buffer;
  cout << "\n";
} 

OUTPUT:
- - - - - -
The string before calling StrTrim: _!ABCDEFG#
The string after calling StrTrim: BCDEFG