c# - IS vs. AS vs. IsAssignableFrom - What are the differences when checking for objectTypes and Interfaces? -

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i'm sort of new c# , wondering if me out.

the scenario: 

public bool objectimplementsspecificinterface (object obj) {     // 1.     if (obj iexampleinterface)      {         return true;     }      // 2.     var tmp = obj iexampleinterface;     if (tmp != null)      {         return true;     }      // 3.     if (typeof(iexampleinterface).isassignablefrom (obj.gettype ()))      {         return true;     } }

the goal: determine wether object o implements given interface-definition iexampleinterface or not.

the questions:

  • which implementation best practice?
  • disregarding first question, 1 technically correct?
  • what specific differences in operators? msdnaa isn't detailed on them.
  • which call takes longest / shortest?

  1. var impinterface = obj isampleinterface;
  2. what mean "technically" ? work. if want ois know whether implments interface, that's is for. if want new variable cast interface, use as.
  3. is determines if object derives type , returns boolean. as attempts cast object type, , return new variable cast type, or null if cannot. (but know question).
  4. as should take longer, if cast works.

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