direct initialization

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[modifier] Syntaxe

[modifier] Explication

• Si T est un type de classe, les constructeurs de T sont examinés et la meilleure correspondance est sélectionné par la résolution de surcharge. Le constructeur est alors appelée pour initialiser l'objet .

  Original:

  If T is a class type, the constructors of T are examined and the best match is selected by overload resolution. The constructor is then called to initialize the object.

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• Autrement, si T est un type non-classe, conversions standard sont utilisés, si nécessaire, à convertir la valeur de other à la version CV-inconditionnel de T .

  Original:

  Otherwise, if T is a non-class type, conversions standard are used, if necessary, to convert the value of other to the cv-unqualified version of T.

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[modifier] Notes

[modifier] Exemple

#include <string>
#include <iostream>
#include <memory>
 
struct Foo {
    int mem;
    explicit Foo(int n) : mem(n) {}
};
 
int main()
{
    std::string s1("test"); // constructor from const char*
    std::string s2(10, 'a');
 
    std::unique_ptr<int> p(new int(1)); // OK: explicit constructors allowed
//  std::unique_ptr<int> p = new int(1); // error: constructor is explicit
 
    Foo f(2); // f is direct-initialized:
              // constructor parameter n is copy-initialized from the rvalue 2
              // f.mem is direct-initialized from the parameter n
//  Foo f2 = 2; // error: constructor is explicit
 
    std::cout << s1 << ' ' << s2 << ' ' << *p << ' ' << f.mem  << '\n';
}

test aaaaaaaaaa 1 2

[modifier] Voir aussi

• initialisation par défaut
• copier initialisation
• initialisation d'agrégats
• liste d'initialisation