clojure.core/nth

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Type: function Added: Clojure 1.0 Examples: 2 Runnable: 1

([coll index] [coll index not-found])

Returns the value at the index. get returns nil if index out of bounds, nth throws an exception unless not-found is supplied. nth also works for strings, Java arrays, regex Matchers and Lists, and, in O(n) time, for sequences.

Examples

by MrHus on 2010-07-18 . May have evaluation errors. ▶

; Note that nth uses zero-based indexing, so that ; (first my-seq) <=> (nth my-seq 0) (def my-seq ["a" "b" "c" "d"]) (nth my-seq 0) ; => "a" (nth my-seq 1) ; => "b" (nth [] 0) ; => IndexOutOfBoundsException ... (nth [] 0 "nothing found") ; => "nothing found" (nth [0 1 2] 77 1337) ; => 1337

by st-keller on 2016-09-12 ▶

(nth ["last"] -1 "this is not perl") ; => "this is not perl"

Note by pesterhazy

Rather than throwing an exception, (nth nil n) returns nil for any number n.

Note by beoliver

Floats are treated as indexes (nth [0 1] 1.9) returns the element at index 1. At first glance it may seem as though they are always rounded down. However due to floating point precision (nth [0 1] 1.9999999999999999) will raise an IndexOutOfBoundsException.

See also

• clojure.core/first (2)
• clojure.core/second
• clojure.core/nthnext (2)
• clojure.core/get (8)
• clojure.core/take-nth (2)
• clojure.core/nthrest (4)
• clojure.core/rand-nth (0)

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