how to count properts is null in model c# code example

Example: if property is null then c#

The null-conditional operators are short-circuiting.
That is, if one operation in a chain of conditional member or element 
access operations returns null, the rest of the chain doesn't execute. 
In the following example, B is not evaluated if A evaluates to null 
and C is not evaluated if A or B evaluates to null:
CODE
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A?.B?.Do(C);
A?.B?[C];