How to use the string::operator> Standard Template Library (STL) function in Visual C++ (158201)


The information in this article applies to:

  • The Standard C++ Library, when used with:
    • Microsoft Visual C++, 32-bit Enterprise Edition 4.2
    • Microsoft Visual C++, 32-bit Enterprise Edition 5.0
    • Microsoft Visual C++, 32-bit Enterprise Edition 6.0
    • Microsoft Visual C++, 32-bit Professional Edition 4.2
    • Microsoft Visual C++, 32-bit Professional Edition 5.0
    • Microsoft Visual C++, 32-bit Professional Edition 6.0
    • Microsoft Visual C++, 32-bit Learning Edition 6.0
    • Microsoft Visual C++ .NET (2002)
    • Microsoft Visual C++ .NET (2003)
    • Microsoft Visual C++ 2005 Express Edition
This article was previously published under Q158201
Note Microsoft Visual C++ .NET 2002 and Microsoft Visual C++ .NET 2003 support both the managed code model that is provided by the Microsoft .NET Framework and the unmanaged native Microsoft Windows code model. The information in this article applies only to unmanaged Visual C++ code. Microsoft Visual C++ 2005 supports both the managed code model that is provided by the Microsoft .NET Framework and the unmanaged native Microsoft Windows code model.

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 returning 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
// 
// StringGreaterThan.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 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>

#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[]="ABCD";
   char CP4[]="abc";

   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);  // False  (calls function 1)

   cout << "S1>CP4 returned ";
   trueFalse(S1>CP4);  // False   (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 ABCD
CP4 is abc
S1>CP1 returned False
S1>CP2 returned False
S1>CP4 returned False
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.
Modification Type:MajorLast Reviewed:1/5/2006
Keywords:kbhowto kbcode kbinfo kbSTL kbtemplate KB158201 kbAudDeveloper
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