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I'm reading "Programming in Lua" book and I don't understand exercise 2.1:
What is the value of the expression
type(nil)==nil?
(You can use Lua to check your answer.) Can you explain this result?"
When I execute this code I get "false" as result. I could not explain this result, from my point of view correct result should be "true". I tried
type(some_undeclared_variable)==nil
and it also gives me "false".
967
The boolean type has two values, false and true, which represent the traditional boolean values. However, they do not hold a monopoly of condition values: In Lua, any value may represent a condition. Conditionals (such as the ones in control structures) consider false and nil as false and anything else as true.
Lua uses nil as a kind of non-value, to represent the absence of a useful value.
The function type() always returns a string, the value of type(nil) is the string "nil", which is not the same as nil, they have different type.
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