Q158203: STL Sample for the string::operation

Article: Q158203
Product(s): Microsoft C Compiler
Version(s): 4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbcode kbVC420 kbVC500 kbVC600 kbDSupport
Last Modified: 29-APR-2002

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The information in this article applies to:

- The Standard C++ Library, included with:
   - Microsoft Visual C++, 32-bit Enterprise Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Professional Edition, versions 4.2, 5.0, 6.0 
   - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
   - Microsoft Visual C++.NET (2002) 
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SUMMARY
=======

The sample code below illustrates how to use the string::operator<= STL
function in Visual C++.

MORE INFORMATION
================

Required Header
---------------

     <string>

Prototype
---------

     Function 1:
        template<class _E, class _TYPE, class _A> inline
        bool operator<=(const basic_string<_E, _TYPE, _A>& LString,
                        const _E *RCharArray);

     Function 2:
        template<class _E, class _TYPE, class _A> inline
        bool operator<=(const _E * LCharArray,
                        const basic_string<_E, _TYPE, _A>& RString);

NOTE: The class/parameter names in the prototype may not match the version in the
header file. Some have been modified to improve readability.

Description
-----------

There are two versions of the string::operator<= function. Both versions are
used to compare a null-terminated character array to a basic_string. They
perform this operation by negating the result of (RString<LCharArray or
RCharArray<LString). For more information on this comparison, please see the
string::operator< function.

Note that this operator does not work with NULL pointer for the character array.
You will need to make sure that the character array is not NULL before you pass
it to the operator.

Sample Code
-----------

  ///////////////////////////////////////////////////////////////////////// 
  // 
  // Compile options needed: /GX
  // 
  // StringLessEqual.cpp : Illustrates how to use the operator<= to compare
  //                       a basic_string variable to a null-terminated
  //                       string.
  // 
  // Functions:
  // 
  //    operator<=   Returns true if the second parameter is not less
  //                 than the first.
  // 
  // Written by Derek Jamison
  // of Microsoft Product Support Services,
  // Copyright (c) 1996 Microsoft Corporation. All rights reserved.
  ///////////////////////////////////////////////////////////////////////// 

  #pragma warning(disable:4786)

  #include <string>
  #include <iostream><BR/>
  using namespace std;

  #if _MSC_VER > 1020   // if VC++ version is > 4.2
     using namespace std;  // std c++ libs implemented in std
     #endif

  void trueFalse(int x)

  {
    cout << (x? "True": "False") << endl;
  }

  void main()

  {

     string S1="DEF";
     char CP1[]="ABC";
     char CP2[]="DEF";
     char CP3[]="DEFG";
     char CP4[]="def";

     cout << "S1 is " << S1 << endl;
     cout << "CP1 is " << CP1 << endl;
     cout << "CP2 is " << CP2 << endl;
     cout << "CP3 is " << CP3 << endl;
     cout << "CP4 is " << CP4 << endl;

     cout << "S1<=CP1 returned ";
     trueFalse(S1<=CP1);  // False  (calls function 1)

     cout << "S1<=CP2 returned ";
     trueFalse(S1<=CP2);  // True   (calls function 1)

     cout << "S1<=CP3 returned ";
     trueFalse(S1<=CP3);  // True   (calls function 1)

     cout << "CP1<=S1 returned ";
     trueFalse(CP1<=S1);  // True   (calls function 2)

     cout << "CP2<=S1 returned ";
     trueFalse(CP2<=S1);  // True   (calls function 2)

     cout << "CP4<=S1 returned ";
     trueFalse(CP4<=S1);  // False   (calls function 2)

  }

Program Output is:

  S1 is DEF
  CP1 is ABC
  CP2 is DEF
  CP3 is DEFG
  CP4 is def
  S1<=CP1 returned False
  S1<=CP2 returned True
  S1<=CP3 returned True
  CP1<=S1 returned True
  CP2<=S1 returned True
  CP4<=S1 returned False

REFERENCES
==========

Visual C++ Books On Line: Visual C++ Books:C/C++:Standard C++ Library Reference.

Additional query words: STL STLSample operator string

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Keywords          : kbcode kbVC420 kbVC500 kbVC600 kbDSupport 
Technology        : kbVCsearch kbAudDeveloper kbVCLibrary
Version           : :4.2,5.0,6.0
Issue type        : kbinfo

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