

MemberQ
Details and Options

- form can be a pattern.
- The first argument of MemberQ can have any head, not necessarily List.
- MemberQ[list,form] immediately tests whether any expression in list matches form; Element[x,dom] asserts that x is an element of the symbolic domain dom.
- MemberQ uses standard level specifications:
-
n levels 1 through n Infinity levels 1 through Infinity {n} level n only {n1,n2} levels n1 through n2 - The default value for levelspec in MemberQ is {1}.
- A positive level n consists of all parts of expr specified by n indices.
- A negative level -n consists of all parts of expr with depth n.
- Level -1 consists of numbers, symbols, and other objects that do not have subparts.
- Level 0 corresponds to the whole expression.
- With the option setting Heads->True, MemberQ looks at heads of expressions and their parts.
- MemberQ works on associations, testing values but not keys.
- MemberQ[form][expr] is equivalent to MemberQ[expr,form].
- Parallelize[MemberQ[list,form]] computes MemberQ[list,form] in parallel on all subkernels. »
Examples
open all close allScope (6)
Properties & Relations (1)
Compute MemberQ in parallel:
See Also
SubsetQ FreeQ MatchQ Element Count Cases IntervalMemberQ KeyExistsQ ContainsAny
Function Repository: ContainsQ
Related Guides
History
Introduced in 1988 (1.0) | Updated in 1999 (4.0) ▪ 2014 (10.0)
Text
Wolfram Research (1988), MemberQ, Wolfram Language function, https://reference.wolfram.com/language/ref/MemberQ.html (updated 2014).
CMS
Wolfram Language. 1988. "MemberQ." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2014. https://reference.wolfram.com/language/ref/MemberQ.html.
APA
Wolfram Language. (1988). MemberQ. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/MemberQ.html
BibTeX
@misc{reference.wolfram_2025_memberq, author="Wolfram Research", title="{MemberQ}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/MemberQ.html}", note=[Accessed: 08-August-2025]}
BibLaTeX
@online{reference.wolfram_2025_memberq, organization={Wolfram Research}, title={MemberQ}, year={2014}, url={https://reference.wolfram.com/language/ref/MemberQ.html}, note=[Accessed: 08-August-2025]}