c# - ToString on null string -

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why second 1 of these produce exception while first 1 doesn't?

string s = null; messagebox.show(s); messagebox.show(s.tostring());

updated - exception can understand, puzzling bit (to me) why first part doesn't show exception. isn't messagebox, illustrated below.

eg :

string s = null, msg; msg = "message " + s; //no error msg = "message " + s.tostring(); //error

the first part appears implicitly converting null blank string.

because cannot call instance method tostring() on null reference.

and messagebox.show() implemented ignore null , print out empty message box.


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