STRLEN

Available since 2.2.0.

Time complexity: O(1)

Returns the length of the string value stored at key. An error is returned when key holds a non-string value.

*Return value

Integer reply: the length of the string at key, or 0 when key does not exist.

redis> SET mykey "Hello world"

OK

redis> STRLEN mykey

(integer) 11

redis> STRLEN nonexisting

(integer) 0