---
name: "memcached_exist_by_key"
section: "3"
platform: "linux"
package: "libmemcached-awesome"
version: "1.1.4-4"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/memcached_exist_by_key"
---

# memcached\_exist\_by\_key(3)

libmemcached Documentation

## NAME

memcached\_exist\_by\_key - libmemcached Documentation

## SYNOPSIS

- **#include \<libmemcached/memcached.h\>**

  Compile and link with -lmemcached

- **memcached\_return\_t \<#\_CPPv418memcached\_return\_t\> memcached\_exist(memcached\_st \<#\_CPPv412memcached\_st\> \*ptr, char \*key, size\_t \*key\_length)**

  - **memcached\_return\_t \<#\_CPPv418memcached\_return\_t\> memcached\_exist\_by\_key(memcached\_st \<#\_CPPv412memcached\_st\> \*ptr, char \*group\_key, size\_t \*group\_key\_length, char \*key, size\_t \*key\_length)**

  - **Parameters**

    - •

      **ptr** -- pointer to an initialized **memcached\_st** \<#\_CPPv412memcached\_st\> struct

    - •

      **group\_key** -- the key namespace

    - •

      **group\_key\_length** -- length of the **group\_key** without any terminating zero

    - •

      **key** -- the key to check

    - •

      **key\_length** -- length of the **key** without any terminating zero

  - **Returns**

    **memcached\_return\_t** \<#\_CPPv418memcached\_return\_t\> indicating success

Added in version 0.53.

## DESCRIPTION

**memcached\_exist()** can be used to check if a key exists.

## RETURN VALUE

- **MEMCACHED\_SUCCESS \<#\_CPPv4N18memcached\_return\_t17MEMCACHED\_SUCCESSE\>**

  The key exists.

- **MEMCACHED\_NOTFOUND \<#\_CPPv4N18memcached\_return\_t18MEMCACHED\_NOTFOUNDE\>**

  The key was not found.

## SEE ALSO

**[memcached(1)](/memcached/1.md) \<https://linux.die.net/man/1/memcached\>** **[libmemcached(3)](/libmemcached/3.md) \<https://linux.die.net/man/3/libmemcached\>** **[memcached\_strerror(3)](/memcached_strerror/3.md) \<https://linux.die.net/man/3/memcached\_strerror\>**