Verwenden der STL-Funktionen vector::erase, vector::empty und vector::p ush_back in Visual C++

In diesem Artikel wird die Verwendung der vector::erase Funktion, der vector::empty Funktion und der vector::push_back STL-Funktionen (Standard Template Library) in Visual C++ veranschaulicht. Die Informationen gelten nur für nicht verwalteten Visual C++-Code.

Ursprüngliche Produktversion: Visual C++
Ursprüngliche KB-Nummer: 158612

Erforderlicher Header

<vector>

Prototypen

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;

Beschreibung

Das Beispiel deklariert einen leeren Vektor von ganzen Zahlen. Sie fügt dem Vektor 10 ganze Zahlen hinzu und zeigt dann den Inhalt des Vektors an. Es löscht das sechste Element mithilfe von erase und zeigt dann den Inhalt des Vektors erneut an. Es löscht die restlichen Elemente mithilfe einer anderen Form des Löschens und zeigt dann den (jetzt leeren) Vektor erneut an. Die ShowVector Routine verwendet die leere Funktion, um zu bestimmen, ob der Inhalt des Vektors generiert werden soll.

Beispielcode

In Visual C++ .NET und Visual C++ ist /EHsc standardmäßig festgelegt und entspricht /GX.

//////////////////////////////////////////////////////////////////////
// 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.
// 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 ;
}

Programmausgabe:

theVector [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
theVector [ 0, 1, 2, 3, 4, 6, 7, 8, 9 ]
theVector is empty.

References

vector::empty, vector::erase und vector::p ush_back