The following sample code illustrates how to use two
vector::erase functions, the vector::empty function, and the vector::push_back
STL functions in Visual C++.
Required header
Prototypes
template<class _TYPE, class _A>
void vector::push_back(const _TYPE& X);
template<class _TYPE, class _A>
iterator vector::erase(iterator Iterator);
template<class _TYPE, class _A>
iterator vector::erase(iterator First, iterator Last);
template<class _TYPE, class _A>
bool vector::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.
Description
The sample declares an empty vector of integers. It adds 10
integers to the vector, then displays the contents of the vector. It deletes
the sixth element by using erase, and then displays the contents of the vector
again. It deletes the rest of the elements using a different form of erase,
then displays the vector (now empty) again. The ShowVector routine uses the
empty function to determine whether to generate the contents of the vector.
Sample code
Note The first line in the sample code is:
// Compile options needed: /GX
In Visual C++
.NET and in Visual C++ 2005, /EHsc is set by default and is
equivalent to /GX.
Note In Visual C++ 2005, you must change the code from
const ARRAY_SIZE = 10; to
const int ARRAY_SIZE = 10; if you want to run the sample code.
//////////////////////////////////////////////////////////////////////
//
// Compile options needed: /GX
//
// Empty.cpp -- Illustrates the vector::empty and vector::erase
// functions.
// Also demonstrates the vector::push_back function.
//
// Functions:
//
// vector::empty - Returns true if vector has no elements.
//
// vector::erase - Deletes elements from a vector (single & range).
//
// vector::begin - Returns an iterator to start traversal of the
// vector.
//
// vector::end - Returns an iterator for the last element of the
// vector.
//
// vector::push_back - Appends (inserts) an element to the end of a
// vector, allocating memory for it if necessary.
//
// vector::iterator - Traverses the vector.
//
// Written by Tom Campbell
// of Microsoft Corporation
// 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.
#pragma warning(disable:4786)
#include <iostream>
#include <vector>
#if _MSC_VER > 1020 // if VC++ version is > 4.2
using namespace std; // std c++ libs implemented in std
#endif
typedef vector<int, allocator<int> > INTVECTOR;
const ARRAY_SIZE = 10;
void ShowVector(INTVECTOR &theVector);
void main()
{
// Dynamically allocated vector begins with 0 elements.
INTVECTOR theVector;
// Intialize the vector to contain the numbers 0-9.
for (int cEachItem = 0; cEachItem < ARRAY_SIZE; cEachItem++)
theVector.push_back(cEachItem);
// Output the contents of the dynamic vector of integers.
ShowVector(theVector);
// Using void iterator erase(iterator Iterator) to
// delete the 6th element (Index starts with 0).
theVector.erase(theVector.begin() + 5);
// Output the contents of the dynamic vector of integers.
ShowVector(theVector);
// Using iterator erase(iterator First, iterator Last) to
// delete a range of elements all at once.
theVector.erase(theVector.begin(), theVector.end());
// Show what's left (actually, nothing).
ShowVector(theVector);
}
// Output the contents of the dynamic vector or display a
// message if the vector is empty.
void ShowVector(INTVECTOR &theVector)
{
// First see if there's anything in the vector. Quit if so.
if (theVector.empty())
{
cout << endl << "theVector is empty." << endl;
return;
}
// Iterator is used to loop through the vector.
INTVECTOR::iterator theIterator;
// Output contents of theVector.
cout << endl << "theVector [ " ;
for (theIterator = theVector.begin(); theIterator != theVector.end();
theIterator++)
{
cout << *theIterator;
if (theIterator != theVector.end()-1) cout << ", ";
// cosmetics for the output
}
cout << " ]" << endl ;
}Program output
theVector [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
theVector [
0, 1, 2, 3, 4, 6, 7, 8, 9 ]
theVector is empty.
For the same topic about vector::empty, erase, and
push_back , visit the following MSDN Web site:
http://msdn.microsoft.com/en-us/library/b6ezyw32.aspx
(http://msdn.microsoft.com/en-us/library/b6ezyw32.aspx)