# LLEN ```json metadata { "schema_version": 2, "title": "LLEN", "description": "Returns the length of a list.", "categories": ["docs","develop","stack","oss","rs","rc","oss","kubernetes","clients"], "arguments": [{"display_text":"key","key_spec_index":0,"name":"key","type":"key"}], "syntax_fmt": "LLEN key", "complexity": "O(1)", "group": "list", "command_flags": ["readonly","fast"], "acl_categories": ["@read","@list","@fast"], "since": "1.0.0", "arity": 2, "key_specs": [{"RO":true,"begin_search":{"spec":{"index":1},"type":"index"},"find_keys":{"spec":{"keystep":1,"lastkey":0,"limit":0},"type":"range"}}], "tableOfContents": {"sections":[{"id":"required-arguments","title":"Required arguments"},{"id":"examples","title":"Examples"},{"id":"redis-software-and-redis-cloud-compatibility","title":"Redis Software and Redis Cloud compatibility"},{"id":"return-information","title":"Return information"}]} , "codeExamples": [{"codetabsId":"cmds_list-stepllen","commands":[{"acl_categories":["@write","@list","@fast"],"complexity":"O(1)","name":"LPUSH"},{"acl_categories":["@read","@list","@fast"],"complexity":"O(1)","name":"LLEN"}],"description":"Foundational: Get the length of a list using LLEN (returns 0 if key doesn\u0026amp;#39;t exist, useful for checking list size)","difficulty":"beginner","id":"llen","languages":[{"id":"redis-cli","panelId":"panel_redis-cli_cmds_list-stepllen"},{"clientId":"redis-py","clientName":"redis-py","id":"Python","langId":"python","panelId":"panel_Python_cmds_list-stepllen"},{"id":"Node-js","panelId":"panel_Nodejs_cmds_list-stepllen"},{"clientId":"ioredis","clientName":"ioredis","id":"ioredis","langId":"javascript","panelId":"panel_ioredis_cmds_list-stepllen"},{"clientId":"jedis","clientName":"Jedis","id":"Java-Sync","langId":"java","panelId":"panel_Java-Sync_cmds_list-stepllen"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Async","langId":"java","panelId":"panel_Java-Async_cmds_list-stepllen"},{"clientId":"lettuce","clientName":"Lettuce","id":"Java-Reactive","langId":"java","panelId":"panel_Java-Reactive_cmds_list-stepllen"},{"clientId":"go-redis","clientName":"go-redis","id":"Go","langId":"go","panelId":"panel_Go_cmds_list-stepllen"},{"id":"dotnet-Sync (SE-Redis)","panelId":"panel_Csharp-Sync (SERedis)_cmds_list-stepllen"},{"clientId":"predis","clientName":"Predis","id":"PHP","langId":"php","panelId":"panel_PHP_cmds_list-stepllen"},{"clientId":"redis-rb","clientName":"redis-rb","id":"Ruby","langId":"ruby","panelId":"panel_Ruby_cmds_list-stepllen"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Sync","langId":"rust","panelId":"panel_Rust-Sync_cmds_list-stepllen"},{"clientId":"redis-rs","clientName":"redis-rs","id":"Rust-Async","langId":"rust","panelId":"panel_Rust-Async_cmds_list-stepllen"}]}] } ``` ## Code Examples Legend The code examples below show how to perform the same operations in different programming languages and client libraries: - **Redis CLI**: Command-line interface for Redis - **C# (Synchronous)**: StackExchange.Redis synchronous client - **C# (Asynchronous)**: StackExchange.Redis asynchronous client - **Go**: go-redis client - **Java (Synchronous - Jedis)**: Jedis synchronous client - **Java (Asynchronous - Lettuce)**: Lettuce asynchronous client - **Java (Reactive - Lettuce)**: Lettuce reactive/streaming client - **JavaScript (Node.js)**: node-redis client - **PHP**: Predis client - **Python**: redis-py client - **Rust (Synchronous)**: redis-rs synchronous client - **Rust (Asynchronous)**: redis-rs asynchronous client Each code example demonstrates the same basic operation across different languages. The specific syntax and patterns vary based on the language and client library, but the underlying Redis commands and behavior remain consistent. --- Returns the length of the list stored at `key`. If `key` does not exist, it is interpreted as an empty list and `0` is returned. An error is returned when the value stored at `key` is not a list. ## Required arguments
key The name of the key that holds the list.
## Examples Foundational: Get the length of a list using LLEN (returns 0 if key doesn't exist, useful for checking list size) **Difficulty:** Beginner **Commands:** LPUSH, LLEN **Complexity:** - LPUSH: O(1) - LLEN: O(1) **Available in:** Redis CLI, C#, Go, Java (Asynchronous - Lettuce), Java (Reactive - Lettuce), Java (Synchronous - Jedis), JavaScript (Node.js), JavaScript (Node.js), PHP, Python, Ruby, Rust (Asynchronous), Rust (Synchronous) ##### Redis CLI ``` redis> LPUSH mylist "World" (integer) 1 redis> LPUSH mylist "Hello" (integer) 2 redis> LLEN mylist (integer) 2 ``` ##### C# ```csharp long lLenResult1 = db.ListLeftPush("mylist", "World"); Console.WriteLine(lLenResult1); // >>> 1 long lLenResult2 = db.ListLeftPush("mylist", "Hello"); Console.WriteLine(lLenResult2); // >>> 2 long lLenResult3 = db.ListLength("mylist"); Console.WriteLine(lLenResult3); // >>> 2 ``` ##### Go ```go lPushResult1, err := rdb.LPush(ctx, "mylist", "World").Result() if err != nil { panic(err) } fmt.Println(lPushResult1) // >>> 1 lPushResult2, err := rdb.LPush(ctx, "mylist", "Hello").Result() if err != nil { panic(err) } fmt.Println(lPushResult2) // >>> 2 lLenResult, err := rdb.LLen(ctx, "mylist").Result() if err != nil { panic(err) } fmt.Println(lLenResult) // >>> 2 ``` ##### Java (Asynchronous - Lettuce) ```java CompletableFuture llen = asyncCommands.lpush("mylist", "World").thenCompose(res11 -> { System.out.println(res11); // >>> 1 return asyncCommands.lpush("mylist", "Hello"); }).thenCompose(res12 -> { System.out.println(res12); // >>> 2 return asyncCommands.llen("mylist"); }) .thenAccept(res13 -> System.out.println(res13)) // >>> 2 .toCompletableFuture(); ``` ##### Java (Reactive - Lettuce) ```java Mono llen = reactiveCommands.lpush("mylist", "World").doOnNext(res11 -> { System.out.println(res11); // >>> 1 }).flatMap(res11 -> reactiveCommands.lpush("mylist", "Hello")).doOnNext(res12 -> { System.out.println(res12); // >>> 2 }).flatMap(res12 -> reactiveCommands.llen("mylist")).doOnNext(res13 -> { System.out.println(res13); // >>> 2 }).then(); ``` ##### Java (Synchronous - Jedis) ```java long lLenResult1 = jedis.lpush("mylist", "World"); System.out.println(lLenResult1); // >>> 1 long lLenResult2 = jedis.lpush("mylist", "Hello"); System.out.println(lLenResult2); // >>> 2 long lLenResult3 = jedis.llen("mylist"); System.out.println(lLenResult3); // >>> 2 ``` ##### JavaScript (Node.js) ```javascript const res11 = await client.lPush('mylist', 'World'); console.log(res11); // 1 const res12 = await client.lPush('mylist', 'Hello'); console.log(res12); // 2 const res13 = await client.lLen('mylist'); console.log(res13); // 2 ``` ##### JavaScript (Node.js) ```javascript const res11 = await redis.lpush('mylist', 'World'); console.log(res11); // >>> 1 const res12 = await redis.lpush('mylist', 'Hello'); console.log(res12); // >>> 2 const res13 = await redis.llen('mylist'); console.log(res13); // >>> 2 ``` ##### JavaScript (Node.js) ```javascript const res11 = await client.lPush('mylist', 'World'); console.log(res11); // 1 const res12 = await client.lPush('mylist', 'Hello'); console.log(res12); // 2 const res13 = await client.lLen('mylist'); console.log(res13); // 2 ``` ##### JavaScript (Node.js) ```javascript const res11 = await redis.lpush('mylist', 'World'); console.log(res11); // >>> 1 const res12 = await redis.lpush('mylist', 'Hello'); console.log(res12); // >>> 2 const res13 = await redis.llen('mylist'); console.log(res13); // >>> 2 ``` ##### PHP ```php $res11 = $r->lpush('mylist', 'World'); echo $res11 . PHP_EOL; // >>> 1 $res12 = $r->lpush('mylist', 'Hello'); echo $res12 . PHP_EOL; // >>> 2 $res13 = $r->llen('mylist'); echo $res13 . PHP_EOL; // >>> 2 ``` ##### Python ```python res11 = r.lpush("mylist", "World") print(res11) # >>> 1 res12 = r.lpush("mylist", "Hello") print(res12) # >>> 2 res13 = r.llen("mylist") print(res13) # >>> 2 ``` ##### Ruby ```ruby res11 = r.lpush('mylist', 'World') puts res11 # >>> 1 res12 = r.lpush('mylist', 'Hello') puts res12 # >>> 2 res13 = r.llen('mylist') puts res13 # >>> 2 ``` ##### Rust (Asynchronous) ```rust if let Ok(res11) = r.lpush("mylist", "World").await { let res11: i32 = res11; println!("{res11}"); // >>> 1 } if let Ok(res12) = r.lpush("mylist", "Hello").await { let res12: i32 = res12; println!("{res12}"); // >>> 2 } if let Ok(res13) = r.llen("mylist").await { let res13: i32 = res13; println!("{res13}"); // >>> 2 } ``` ##### Rust (Synchronous) ```rust if let Ok(res11) = r.lpush("mylist", "World") { let res11: i32 = res11; println!("{res11}"); // >>> 1 } if let Ok(res12) = r.lpush("mylist", "Hello") { let res12: i32 = res12; println!("{res12}"); // >>> 2 } if let Ok(res13) = r.llen("mylist") { let res13: i32 = res13; println!("{res13}"); // >>> 2 } ``` ## Redis Software and Redis Cloud compatibility | Redis
Software | Redis
Cloud | Notes | |:----------------------|:-----------------|:------| | ✅ Standard
✅ Active-Active | ✅ Standard
✅ Active-Active | | ## Return information **RESP2:** [Integer reply](../../develop/reference/protocol-spec#integers): the length of the list. **RESP3:** [Integer reply](../../develop/reference/protocol-spec#integers): the length of the list.