c# - Explicit assignment of null -

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string s1; string s2 = null;  if (s1 == null) // compile error if (s2 == null) // ok

i don't understand why explicit assignment needed. whats difference between null variable , unassigned variable? assumed unassigned variables assigned null runtime/compiler anyway. if they're not null, they?

unassigned members automatically initialized default values (which null reference in case string).

unassigned local variables not assigned value , trying access possibly unassigned variable give compile error.


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