UnsameQ¶

Status: Stable

documented, exercised by the test suite and/or worked examples, with no known limitations recorded.

Description¶

lhs =!= rhs or UnsameQ[lhs, rhs] is the negation of SameQ: True iff lhs and rhs are not structurally identical.

Examples (2)¶

Every input below was run against the current Mathilda build and its output recorded.

Applications (2)¶

In[1]:= a =!= b
Out[1]= True

In[2]:= a =!= a
Out[2]= False

Implementation notes¶

builtin_unsameq is the negation of structural identity over all argument pairs. With fewer than two arguments it returns True; otherwise it checks every pair (i,j) with expr_eq and returns False as soon as any two are structurally equal, else True. Like SameQ it uses no numeric coercion and always yields a definite boolean.

Attributes: Protected.

References¶

See also: SameQ

Source: src/comparisons.c
Specification: docs/spec/builtins/comparisons.md
Tests: tests/test_comparisons.c

Notes & additional examples¶

Notes¶

UnsameQ (=!=) is the structural negation of SameQ; it always decides to True or False.