Use as funções de STL vector::erase, vector::empty e vector::p ush_back no Visual C++

Este artigo ilustra como usar a vector::erase função, a vector::empty função e as vector::push_back funções STL (Biblioteca de Modelos Padrão) no Visual C++. As informações se aplicam apenas ao código do Visual C++ não gerenciado.

Versão original do produto: Visual C++
Número de KB original: 158612

Cabeçalho necessário

<vector>

Protótipos

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;

Descrição

O exemplo declara um vetor vazio de inteiros. Ele adiciona 10 inteiros ao vetor e exibe o conteúdo do vetor. Ele exclui o sexto elemento usando apagamento e exibe o conteúdo do vetor novamente. Ele exclui o restante dos elementos usando uma forma diferente de apagamento e exibe o vetor (agora vazio) novamente. A ShowVector rotina usa a função vazia para determinar se deve gerar o conteúdo do vetor.

Código de exemplo

No Visual C++ .NET e no Visual C++, /EHsc é definido por padrão e é equivalente a /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 ;
}

Saída do programa:

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

Referências

vector::empty, vector::erase e vector::p ush_back