typeid operator — cppreference.com
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Requêtes informations d'un type .
Original:
Queries information of a type.
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Utilisé lorsque le type réel d'une classe de base virtuel doit être connu .
Original:
Used where the actual type of a virtuel base class must be known.
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Syntaxe
typeid( type )
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(1) | ||||||||
typeid( expression )
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<typeinfo>-tête doit être inclus avant d'utiliser l'opérateur typeid .
Original:
Header <typeinfo> must be included before using typeid operator.
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Les deux versions renvoyer un objet de type .. const std::type_info&
Original:
Both versions return an object of type const std::type_info&.
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Explication
1)
renvoie les informations sur le type de type. Le type sera définitivement connu moment de la compilation, sans temps d'exécution est due .
Original:
returns the type information about the type. The type will be definitely known compile time and no runtime overhead is caused.
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2)
expression est évaluée et l'information de type correspondant à la valeur résultante est retournée. Si le expression est dans une classe de base virtuelle, le type réel de la classe est interrogé de façon dynamique avec une surcharge d'exécution. Sinon, le type réel est temps de compilation définitivement connu, sans temps d'exécution est due .
Original:
expression is evaluated and type information corresponding to the resulting value is returned. If the expression is in a virtual base class, the actual type of the class is queried dynamically with some runtime overhead. Otherwise the actual type is definitely known compile time and no runtime overhead is caused.
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