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LPOS

Returns the index of the first occurrence of an element matching the specified value in a list stored at key. If the element is not found or the key does not exist, nil is returned.

Syntax​

LPOS key element [RANK rank]

Details​

  • Available since: 6.2.0
  • Time complexity: O(N) where N is the number of elements in the list.
  • ACL categories: @read, @list, @fast

Example​

Assume we have a list called mylist with elements "a", "b", "c", "b", and "d":

RPUSH mylist "a"
RPUSH mylist "b"
RPUSH mylist "c"
RPUSH mylist "b"
RPUSH mylist "d"

Now, let's find the index of the first occurrence of "b" in mylist:

LPOS mylist "b"

This will output:

1

RESP2/RESP3 Reply​

Integer reply: the index of the first occurrence of the element, or nil if the element is not found.