std::vector::front

<metanoindex/>

 

C++

Suporte ao Compilador

Freestanding and hosted

Linguagem

Headers da Biblioteca Standard

Requerimentos nomeados

Feature test macros (C++20)

Biblioteca de suporte de língua

Biblioteca de conceitos (C++20)

Biblioteca de diagnósticos

Biblioteca de utilitários em geral

Biblioteca de strings

Biblioteca de containers

Ranges library (C++20)

Biblioteca de iteradores

Biblioteca de algorítmos

Biblioteca numérica

Biblioteca de localizações

Biblioteca de input/output

Biblioteca de sistema de arquivo (C++17)

Biblioteca de expressões regulares (C++11)

Biblioteca de operações atômicas (C++11)

Biblioteca de suporte de thread (C++11)

Especificações Técnicas

Índice de symbolos

Bibliotecas externas

 

Recipientes biblioteca

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

map

multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

priority_queue

 

std::vector

Funções de membro Original: Member functions The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

vector::vector

vector::~vector

vector::operator=

vector::assign

vector::get_allocator

acesso. Elemento Original: Element access The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

vector::at

vector::operator[]

vector::front

vector::back

vector::data (C++11)

Iteradores Original: Iterators The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

vector::begin vector::cbegin (C++11)

vector::end vector::cend (C++11)

vector::rbegin vector::crbegin (C++11)

vector::rend vector::crend (C++11)

Capacidade Original: Capacity The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

vector::empty

vector::size

vector::max_size

vector::reserve

vector::capacity

vector::shrink_to_fit (C++11)

Modificadores Original: Modifiers The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

vector::clear

vector::insert

vector::emplace (C++11)

vector::erase

vector::push_back

vector::emplace_back (C++11)

vector::pop_back

vector::resize

vector::swap

 

<tbody> </tbody>

reference front();
const_reference front() const;

Devolve uma referência para o primeiro elemento no contentor.

Original:

Returns a reference to the first element in the container.

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Chamando front em um recipiente vazio é indefinido.

Original:

Calling front on an empty container is undefined.

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Parâmetros

(Nenhum)

Original:

(none)

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Valor de retorno

a referência ao primeiro elemento

Original:

reference to the first element

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Complexidade

Constante

Original:

Constant

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Notas

Para uma c recipiente, o c.front() expressão é equivalente a *c.begin().

Original:

For a container c, the expression c.front() is equivalent to *c.begin().

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

Exemplo

O código a seguir usa front para exibir o primeiro elemento de um std::vector<char>:

Original:

The following code uses front to display the first element of a std::vector<char>:

The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

#include <vector>
#include <iostream>
 
int main()
{
    std::vector<char> letters {'o', 'm', 'g', 'w', 't', 'f'};
 
    if (!letters.empty()) {
        std::cout << "The first character is: " << letters.front() << '\n';
    }  
}

Saída:

The first character is o

See also

back	access the last element (função pública membro)