null
¶
Is null
null x null[x]
Returns 1b
where x
is null.
Applies to all data types except enums, and to items of lists, dict values and table columns.
null
is an atomic function.
q)null 0 0n 0w 1 0n
01001b
q)where all null ([] c1:`a`b`c; c2:0n 0n 0n; c3:10 0N 30)
,`c2
Enums always show as non-null.
q)a:``a
q)`=`a$` / non-enumerated and enumerated null symbol show as equivalent
1b
q)null` / null symbol behaves as expected
1b
q)null`a$` / enumeration of null symbol does not
0b
The intention was not to have nulls in the enums. That value is used to indicate out of range. (Think of them as a way to represent foreign keys.) To test for an enumeration backed by a null symbol, one can use the equality test – but at the cost of CPU cycles:
q)a:10000000?`8
q)v:`a$a
q)\ts null v
18 16777344
q)\ts `=v
66 268435648
null
is a multithreaded primitive.