Tiny Tip: is vs. as

Today’s tip is a quick look at both not widely used C# operators and why prefer one to another..


Casting using is-operator: 


if(p is Product) // CLR?: Could i cast this to product?


{


      Product x = (Product)p; // CLR again??: Could i cast this to Product?


}


This work but comes with performance cost so you better use the as-operator as follows:


Casting using as-operator:


Product x = p as Product; // CLR?: Could i cast this to product?


if(x!=null)


{


     // your logic here..


}


Here the CLR checks for type compatibility only one time and as-operator never throw an exception only the result will be null if it’s not type compatible.

2 thoughts on “Tiny Tip: is vs. as”

  1. This is not necessarily true. In reality there may be a low chance that p is of type Product, in which case using “is”, is actually slightly faster. We’re talking about billionths of seconds here, so it only matters for really big loops.

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