On comparing null and 0
I recently learned about this surprising behavior in JavaScript:
null > 0
=> false
null < 0
=> false
null == 0
=> false
null >= 0
=> true
There is, of course, a technical reason behind this. But still… it’s pretty weird.
It got me curious about how my other languages would behave comparing null and 0.
Ruby
I ran this code in the Rails console:
nil > 0
=> NoMethodError: undefined method `>' for nil:NilClass
0 < nil
=> ArgumentError: comparison of Integer with nil failed
Reasonable, though of course they are undesirable runtime errors.
C#
System.Console.WriteLine(0 < null); // False
System.Console.WriteLine(null > 0); // False
This one actually surprised me by compiling at all. It did compile with warnings, though:
Comparing with null of type ‘int?’ always produces ‘false’
I’ve been less active in C# lately, but I honestly assumed it this would be a compiler error. TIL!
F#
printfn "%b" (0 < null)
printfn "%b" (null > 0)
Only F# treated this (properly, whereas I’m concerned) as a compile-time error:
The type ‘int’ does not have ‘null’ as a proper value.
Looks like F# wins this micro-competition. 🏆