What does ~= do in Lua?... See it everywhere but still confused on what it does
Hello, I have a question. What does this do? ~=
Looks like an arithmetic operator, but not sure.
I've seen it used like this before.
local exampleVarriable = "Example"
if exampleVarriable ~= nil then
print("Something...")
end
4 answers
The ~= symbol means not equal
So basically saying
if exampleVarriable is not equal to nil then print("something...")
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~= means not equal. For example, 1 ~= 2
If both numbers(or strings, or tables, etc.) are not equal to each other, it will return true. If both are equal, it will return false.
~= is Lua's inequality comparison operator.
a ~= b will evaluate to true if a and b are not equal. However if either a or b have a metatable with an __eq field set to a function then Lua will call that function instead. To avoid calling this function and perform a raw comparison, Lua provides a function call rawequal which compares a and b without invoking the __eq metamethod.
This last bit of information is really only of use to you if you make use of metatables, but I found it interesting to bring up anyway.
An interesting thing to note about equality comparisons is that {} == {} will never be true, as tables are compared by reference and not by value. This means that a variable holding a table will only ever be equal to another if the second refers to the same table in memory:
local t1 = {}
local t2 = {}
print(t1 == t2) -- false
t3 = t1
print(t1 == t3) -- true
Yet another thing to note is that NaN -- a special number constant meaning "Not a Number" and returned by undefined math operations -- equals nothing, not even itself.
local x = 0/0 print(x ~= x) -- true
