It depends on the context. What was described as NA in that example by be NULL or NaN in another application. For example, excel power query would call it NULL, which I find baffling having used R.
It’s basically Wild West out there. There are no rules, there is only chaos.
But what about empty string, and what’s the difference between NULL and “NULL”? Is NaN a null number?
So there is the “it depends” answer, but generally:
NULL means a value doesn’t exist in memory, usually because the variable was never given a value, or because the variable was given the null value.
“NULL” is a string with the word null written in all caps. It’s not an empty string and it’s not NULL. It’s a value with the word “NULL”.
“” is an empty string. It’s not NULL because technically it’s fully initialized value. It’s a string that has a length of 0 characters.
NaN is not a number. A value could or could not exist, but if it’s not a number then if you check for a number you could get NaN.
It depends on the context. What was described as NA in that example by be NULL or NaN in another application. For example, excel power query would call it NULL, which I find baffling having used R.
It’s basically Wild West out there. There are no rules, there is only chaos.
Excel probably thinks null is Jan-01-1900.
And empty cells are zeroes. 🤯