LLEN

Syntax

LLEN key

Description

The LLEN command returns the number of elements in a list. If the key does not exist, it returns 0. If the key exists but is not a list, an error is returned.

Arguments

• key (required): The name of the list key.

Return Value

Returns an Integer: The length of the list, or 0 if the key doesn't exist.

Examples

Getting Length of Existing List

RPUSH mylist "a" "b" "c"
LLEN mylist

Response:

(integer) 3
(integer) 3

Getting Length of Non-Existent List

LLEN nonexistent

Response:

(integer) 0

Getting Length After Operations

RPUSH mylist "a" "b" "c"
LLEN mylist
LPOP mylist
LLEN mylist

Response:

(integer) 3
(integer) 3
"a"
(integer) 2

Empty List

LPUSH mylist "item"
LPOP mylist
LLEN mylist

Response:

(integer) 1
"item"
(integer) 0

Notes

• Returns 0 if the key doesn't exist
• Returns 0 if the list is empty
• Returns a WRONGTYPE error if the key exists but is not a list
• The length is always a non-negative integer

Use Cases

• Queue Monitoring: Check how many items are in a queue
• Validation: Verify that a list has the expected number of elements
• Conditional Logic: Check if a list is empty before processing
• Statistics: Track the size of lists over time

Related Commands

• LPUSH - Prepend values to a list
• RPUSH - Append values to a list
• LRANGE - Get a range of elements from a list