38-2

string::operator+ (STL Sample)

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

Required Header:
<string>

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 do 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.
//////////////////////////////////////////////////////////////////////

#pragma warning(disable:4786)
#include <string>
#include <iostream>

using namespace std ;

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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38-2

string::operator+ (STL Sample)