LPOP

Syntax

LPOP key [count]

Description

The LPOP command removes and returns elements from the left (head) of a list. If a count is specified, multiple elements are removed and returned. If the key does not exist, an empty array is returned.

Arguments

• key (required): The name of the list key.
• count (optional): The number of elements to pop. If not specified, defaults to 1. Must be a positive integer.

Return Value

Returns an Array:

• An array of popped elements (in the order they were in the list)
• An empty array if the key doesn't exist or the list is empty

Examples

Popping a Single Element

LPUSH mylist "a" "b" "c"
LPOP mylist

Response:

(integer) 3
"c"

Popping Multiple Elements

LPUSH mylist "d" "c" "b" "a"
LPOP mylist 2

Response:

(integer) 4
1) "a"
2) "b"

Popping from Empty List

LPOP emptylist

Response:

(nil)

Popping More Than Available

LPUSH mylist "a" "b"
LPOP mylist 5

Response:

(integer) 2
1) "a"
2) "b"

Note: If you request more elements than are available, all available elements are returned.

Notes

• Elements are removed from the left (head) of the list
• Returns elements in the order they were in the list
• If count is greater than the list length, all elements are returned
• Returns an empty array if the key doesn't exist
• Returns a WRONGTYPE error if the key exists but is not a list

Use Cases

• Stacks: Implement LIFO (Last In, First Out) operations
• Task Processing: Remove tasks from the front of a queue
• Message Processing: Process messages from the head of a queue
• Recent Items: Remove oldest items from a recent items list

Related Commands

• RPOP - Remove and return elements from the right
• LPUSH - Prepend values to a list
• LRANGE - Get a range of elements from a list