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c#nullvar

Initializing a 'var' to null

Is there any difference in runtime performance between the following variable initializations?

var    x = null as object;
var    x = (object) null;
object x = null;
Solution

  • I believe no, since there is no difference in compiled IL.

    var    x = null as object;
var    x1 = (object)null;
object x2 = null;

    gets compiled to

    IL_0001:  ldnull      
IL_0002:  stloc.0     // x
IL_0003:  ldnull      
IL_0004:  stloc.1     // x1
IL_0005:  ldnull      
IL_0006:  stloc.2     // x2

    You can see all the locals are initialized to null using ldnull opcode only, so there is no difference.