---
name: "memchr"
section: "3"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/memchr"
---

# memchr(3)

memory search character

## NAME

memchr - memory search character

## LIBRARY

Standard C library (*libc*, *-lc*)

## SYNOPSIS

```
#include <string.h>  // see memory.h(3head)
```

**void \*memchr(**size\_t n;              **const void** *s***\[***n***\], int** *c***, size\_t** *n***);**

## DESCRIPTION

**memchr**() scans the initial *n* bytes of the memory area pointed to by *s* for the first instance of *c*.

Both *c* and the bytes of the memory area pointed to by *s* are interpreted as *unsigned char*.

## RETURN VALUE

**memchr**() returns a pointer to the matching byte or NULL if the character does not occur in the given memory area.

## ATTRIBUTES

For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md).

| | | |
| --- | --- | --- |
| **Interface** | **Attribute** | **Value** |
| **memchr**() | Thread safety | MT-Safe |

## STANDARDS

C11, POSIX.1-2008.

## HISTORY

POSIX.1-2001, C89, SVr4, 4.3BSD.

## SEE ALSO

[**memory.h**(3head)](/memory.h/3head.md), [**memrchr**(3)](/memrchr/3.md), [**wmemchr**(3)](/wmemchr/3.md)