Article ID: 158085 - Last Review: August 11, 2005 - Revision: 5.1

How to use the list::assign, list::empty, and list::erase STL functions in Visual C++

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This article was previously published under Q158085
NOTE: Microsoft Visual C++ .NET (2002) and Visual C++ .NET (2003) support 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.

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SUMMARY

The sample code below illustrates how to use the list::assign, list::empty, and list::erase STL functions in Visual C++.
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MORE INFORMATION

Required Header

   <list>
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Prototype

   void assign(const_iterator first, const_iterator last);
   void assign(size_type n, const T& x = T());
   iterator erase(iterator it);
   iterator erase(iterator first, iterator last);
   bool empty() const;
NOTE: The class/parameter names in the prototype may not match the version in the header file. Some have been modified to improve readability.
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Description

The first member function replaces the sequence controlled by *this with the sequence [first, last). The second member function replaces the sequence controlled by *this with a repetition of n elements of value x.

The third member function removes the element of the controlled sequence pointed to by it. The fourth member function removes the elements of the controlled sequence in the range [first, last). Both return an iterator that designates the first element remaining beyond any elements removed, or end() if no such element exists.

The last member function returns true for an empty controlled sequence.
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Sample Code

////////////////////////////////////////////////////////////////////// 
// 
// Compile options needed: -GX
// 
// assign.cpp :  Shows the various ways to assign and erase elements
//               from a list<T>.
// 
// Functions:
// 
//    list::assign
//    list::empty
//    list::erase
// 
// Written by Andrew Bradnan
// Copyright (c) 1996 Microsoft Corporation. All rights reserved.
////////////////////////////////////////////////////////////////////// 

#include <list>
#include <iostream>

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

typedef list<int, allocator<int> > LISTINT;

void main()

{

    LISTINT listOne;
    LISTINT listAnother;
    LISTINT::iterator i;

    // Add some data
    listOne.push_front (2);
    listOne.push_front (1);
    listOne.push_back (3);

    listAnother.push_front(4);

    listAnother.assign(listOne.begin(), listOne.end());

    // 1 2 3
    for (i = listAnother.begin(); i != listAnother.end(); ++i)
        cout << *i << " ";
    cout << endl;

    listAnother.assign(4, 1);

    // 1 1 1 1
    for (i = listAnother.begin(); i != listAnother.end(); ++i)
        cout << *i << " ";
    cout << endl;

    listAnother.erase(listAnother.begin());

    // 1 1 1
    for (i = listAnother.begin(); i != listAnother.end(); ++i)
        cout << *i << " ";
    cout << endl;

    listAnother.erase(listAnother.begin(), listAnother.end());
    if (listAnother.empty())
        cout << "All gone\n";

}
Program Output is: 
1 2 3
1 1 1 1
1 1 1
All gone
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REFERENCES

For the same information about list::assign, list::empty, and list::erase, visit the following MSDN Web site:
http://msdn.microsoft.com/en-us/library/csd0eyyx.aspx (http://msdn.microsoft.com/en-us/library/csd0eyyx.aspx)
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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
    • Microsoft Visual C++ 5.0 Professional Edition
    • Microsoft Visual C++ 6.0 Professional Edition
    • Microsoft Visual C++, 32-bit Learning Edition 6.0
    • Microsoft Visual C++ .NET 2002 Standard Edition
    • Microsoft Visual C++ .NET 2003 Standard Edition
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Keywords: 
kbfunctions kbhowto kbcode kbinfo kbstl kbtemplate KB158085
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