std::begin - cppreference.com
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      std::begin

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      <metanoindex/>

       
      C++
       
      Biblioteca Iterator
      Primitivas iterador
      Original:
      Iterator primitives
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      Adaptadores de iterador
      Original:
      Iterator adaptors
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      Iteradores fluxo
      Original:
      Stream iterators
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      Operações iterador
      Original:
      Iterator operations
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      (C++11)
      (C++11)
      Variar de acesso
      Original:
      Range access
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      (C++11)
      (C++11)
       
      <tbody> </tbody>
      Definido no cabeçalho <iterator>
      template< class C > auto begin( C& c ) -> decltype(c.begin());
      		 (1) (desde C++11)
      template< class C > auto begin( const C& c ) -> decltype(c.begin());
      		 (2) (desde C++11)
      template< class T, size_t N > T* begin( T (&array)[N] );
      		 (3) (desde C++11)
      Retorna um iterador para o início do c determinado recipiente ou matriz array.
      Original:
      Returns an iterator to the beginning of the given container c or array array.
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      Parâmetros

      c -
      um recipiente com um método begin
      Original:
      a container with a begin method
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      array -
      uma matriz do tipo arbitrário
      Original:
      an array of arbitrary type
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      Valor de retorno

      um iterador para o início da c ou array
      Original:
      an iterator to the beginning of c or array
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      Notas

      Além de serem incluídos no <iterator>, std::begin é garantido que se tornam disponíveis, se qualquer um dos seguintes cabeçalhos estão incluídos: <array>, <deque>, <forward_list>, <list>, <map>, <regex>, <set>, <string>, <unordered_map>, <unordered_set> e <vector>.
      Original:
      In addition to being included in <iterator>, std::begin is guaranteed to become available if any of the following headers are included: <array>, <deque>, <forward_list>, <list>, <map>, <regex>, <set>, <string>, <unordered_map>, <unordered_set>, and <vector>.
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      Especializações

      Especializações personalizadas de std::begin podem ser fornecidas para as classes que não expõem um adequado begin() função de membro, mas pode ser repetido. Os seguintes especializações já são fornecidas pela biblioteca padrão:
      Original:
      Custom specializations of std::begin may be provided for classes that do not expose a suitable begin() member function, yet can be iterated. The following specializations are already provided by the standard library:
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      (C++11)
      std::begin especializada
      Original:
      specializes std::begin
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      (modelo de função) [edit]
      (C++11)
      std::begin especializada
      Original:
      specializes std::begin
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      (modelo de função) [edit]

      Exemplo

      #include <iostream>
#include <vector>
#include <iterator>

int main() 
{
    std::vector<int> v = { 3, 1, 4 };
    auto vi = std::begin(v);
    std::cout << *vi << '\n'; 

    int a[] = { -5, 10, 15 };
    auto ai = std::begin(a);
    std::cout << *ai << '\n';
}

      Saída: 

      3
-5

      Veja também