default initialization

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[editar] Sintaxe

[editar] Explicação

• Se T é um tipo de classe, o construtor padrão é chamado para fornecer o valor inicial para o novo objeto.

  Original:

  If T is a class type, the construtor padrão is called to provide the initial value for the new object.

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• Se T é um tipo de matriz, cada elemento da matriz é o padrão-inicializado.

  Original:

  If T is an array type, every element of the array is default-initialized.

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• Caso contrário, nada é feito.

  Original:

  Otherwise, nothing is done.

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[editar] Notas

[editar] Exemplo

#include <string>
struct T1 {};
class T2 { 
    int mem;
 public:
    T2() {} // "mem" not in initializer list
};
int n; // This is not default-initialization, the value is zero.
int main()
{
    int n;            // non-class: the value is undeterminate
    std::string s;    // calls default ctor, the value is "" (empty string)
    std::string a[2]; // calls default ctor, creates two empty strings
//    int& r;         // error: default-initializing a reference
//    const int n;    // error: const non-class type
//    const T1 nd;    // error: const class type with implicit ctor
    T1 t1; // ok, calls implicit default ctor
    const T2 t2; // ok, calls the user-provided default ctor 
                 // t2.mem is default-initialized
}

[editar] Veja também

• inicialização direta
• copiar inicialização
• lista de inicialização