Q158206: STL Sample for the string::operator!= Function

Article: Q158206
Product(s): Microsoft C Compiler
Version(s): 4.2,5.0,6.0
Operating System(s): 
Keyword(s): kbcode kbtemplate kbSTL kbVC420 kbVC500 kbVC600 kbDSupport
Last Modified: 04-MAY-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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NOTE: Microsoft Visual C++ NET (2002) supported both the managed code model that is provided by the .NET Framework and the unmanaged native Windows code model. The information in this article applies to unmanaged Visual C++ code only.

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 against a basic_string. They
perform this operation by negating the result of (LString==RCharArray) or
(LCharArray==RString). For more information on this comparison, please see the
string::operator== function.

Notice 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
  // 
  // StringNotEqual.cpp : Illustrates how to use the operator!= to test for
  //                      non-equality of a basic_string variable and a
  //                      null-terminated string.
  // 
  // Functions:
  // 
  //    operator!=   Returns true if the basic_string and the null-
  //                 terminated string are not equal.
  // 
  // 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>

  #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="ABC";
     char CP1[]="ABC";
     char CP2[]="DEF";
     char CP3[]="abc";

     cout << "S1 is " << S1 << endl;
     cout << "CP1 is " << CP1 << endl;
     cout << "CP2 is " << CP2 << endl;
     cout << "CP3 is " << CP3 << 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);  // False  (calls function 2)

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

     cout << "CP3!=S1 returned ";
     trueFalse(CP3!=S1);  // True   (calls function 2)

  }

Program Output is:

  S1 is ABC
  CP1 is ABC
  CP2 is DEF
  CP3 is abc
  S1!=CP1 returned False
  S1!=CP2 returned True
  S1!=CP3 returned True
  CP1!=S1 returned False
  CP2!=S1 returned True
  CP3!=S1 returned True

REFERENCES
==========

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

Additional query words: STL STLSample operator!= string

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

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