Microsoft KB Archive/158207

= How to use the string::operator+ STL function in Visual C++ =

Article ID: 158207

Article Last Modified on 1/9/2006

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APPLIES TO

 The Standard C++ Library, when used with:  Microsoft Visual C++ 4.2 Enterprise Edition

 Microsoft Visual C++ 5.0 Enterprise Edition

 Microsoft Visual C++ 6.0 Enterprise Edition

 Microsoft Visual C++ 4.2 Professional Edition</li></ul>

 Microsoft Visual C++ 5.0 Professional Edition</li></ul>

 Microsoft Visual C++ 6.0 Professional Edition</li></ul>

 Microsoft Visual C++ 6.0 Standard Edition</li></ul>

 Microsoft Visual C++ 2005 Express Edition</li></ul>

 Microsoft Visual C++ .NET 2003 Standard Edition</li></ul>

 Microsoft Visual C++ .NET 2002 Standard Edition</li></ul> </li></ul>

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This article was previously published under Q158207

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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.

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

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

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

Function 3: template<class _E, class _TYPE, class _A> inline basic_string<_E, _TYPE, _A> operator+(const basic_string<_E, _TYPE, _A>& LString,                const _E RChar);

Function 4: template<class _E, class _TYPE, class _A> inline basic_string<_E, _TYPE, _A> operator+(const _E LChar,                const basic_string<_E, _TYPE, _A>& RString);

Function 5: template<class _E, class _TYPE, class _A> inline basic_string<_E, _TYPE, _A> operator+(const basic_string<_E, _TYPE, _A>& LString,                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 five versions of the string::operator+ function. Two functions are used to concatenate a null-terminated character array and a basic_string. Two functions are used to concatenate a character and a basic_string. The last function is used to concatenate two basic_string variables.

Sample code
////////////////////////////////////////////////////////////////////// // // Compile options needed: /GX // // StringPlus.cpp : Illustrates how to use the operator+ to concatenate //                 a null-terminated character array and a basic_string, //                 how to concatenate a character and a basic_string, //                 and how to concatenate two basic_string variables. // // Functions: // //   operator+ : Concatenates a null-terminated character array and //               a basic_string. //   operator+ : Concatenates a character array and a basic_string. //   operator+ : Concatenates two basic_string variables. // // Written by Derek Jamison // of Microsoft Product Support Services, // Copyright (c) 1996 Microsoft Corporation. All rights reserved. //////////////////////////////////////////////////////////////////////

// The debugger can't handle symbols more than 255 characters long. // STL often creates symbols longer than that. // When symbols are longer than 255 characters, the warning is disabled.

using namespace std;
 * 1) pragma warning(disable:4786)
 * 2) include
 * 3) include

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

void main

{

string result; string S1="ABC"; string S2="DEF"; char CP1[]="GHI"; char C='J';

cout << "S1 is " << S1 << endl; cout << "S2 is " << S2 << endl; cout << "CP1 is " << CP1 << endl; cout << "C is " << C << endl;

result=S1+CP1;                          // Function 1  (ABCGHI) cout << "S1+CP1 is " << result << endl;

result=CP1+S1;                          // Function 2  (GHIABC) cout << "CP1+S1 is " << result << endl;

result=S1+S2;                           // Function 3  (ABCDEF) cout << "S1+S2 is " << result << endl;

result=S1+C;                            // Function 4  (ABCJ) cout << "S1+C is " << result << endl;

result=C+S1;                            // Function 5  (JABC) cout << "C+S1 is " << result << endl;

} Program Output is: S1 is ABC S2 is DEF CP1 is GHI C is J S1+CP1 is ABCGHI CP1+S1 is GHIABC S1+S2 is ABCDEF S1+C is ABCJ C+S1 is JABC

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