---
name: "ck_hs_fas"
section: "3"
platform: "linux"
package: "libck-dev"
version: "0.7.2-6"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/ck_hs_fas"
---

# ck\_hs\_fas(3)

fetch and store key in hash set

## NAME

**ck\_hs\_fas** – fetch and store key in hash set

## LIBRARY

Concurrency Kit (libck, -lck)

## SYNOPSIS

**#include \<ck\_hs.h\>**

*bool*\

**ck\_hs\_fas**(*ck\_hs\_t \*hs*, *unsigned long hash*, *const void \*key*, *void \*\*previous*);

## DESCRIPTION

The **ck\_hs\_fas**(*3*) function will fetch and store the key specified by the *key* argument in the hash set pointed to by the *hs* argument. The key specified by *key* is expected to have the hash value specified by the *hash* argument (which was previously generated using the [CK\_HS\_HASH(3)](/CK_HS_HASH/3.md) macro).

If the call to **ck\_hs\_fas**(*3*) was successful then the key specified by *key* was successfully stored in the hash set pointed to by *hs*. The key must already exist in the hash set, and is replaced by *key* and the previous value is stored into the void pointer pointed to by the *previous* argument. If the key does not exist in the hash set then the function will return false and the hash set is unchanged. This function is guaranteed to be stable with respect to memory usage.

## RETURN VALUES

Upon successful completion, **ck\_hs\_fas**(*3*) returns true and otherwise returns false on failure.

## ERRORS

Behavior is undefined if *key* or *hs* are uninitialized.

## SEE ALSO

[ck\_hs\_init(3)](/ck_hs_init/3.md), [ck\_hs\_move(3)](/ck_hs_move/3.md), [ck\_hs\_destroy(3)](/ck_hs_destroy/3.md), [CK\_HS\_HASH(3)](/CK_HS_HASH/3.md), [ck\_hs\_iterator\_init(3)](/ck_hs_iterator_init/3.md), [ck\_hs\_next(3)](/ck_hs_next/3.md), [ck\_hs\_get(3)](/ck_hs_get/3.md), [ck\_hs\_put(3)](/ck_hs_put/3.md), [ck\_hs\_put\_unique(3)](/ck_hs_put_unique/3.md), [ck\_hs\_remove(3)](/ck_hs_remove/3.md), [ck\_hs\_grow(3)](/ck_hs_grow/3.md), [ck\_hs\_rebuild(3)](/ck_hs_rebuild/3.md), [ck\_hs\_gc(3)](/ck_hs_gc/3.md), [ck\_hs\_count(3)](/ck_hs_count/3.md), [ck\_hs\_reset(3)](/ck_hs_reset/3.md), [ck\_hs\_reset\_size(3)](/ck_hs_reset_size/3.md), [ck\_hs\_stat(3)](/ck_hs_stat/3.md)

Additional information available at http://concurrencykit.org/