---
name: "isrune"
section: "3"
platform: "macos"
package: "Libc"
version: "1752.120.2"
release: "macOS 26.5"
platforms: ["freebsd", "macos"]
url: "https://new.carta.tech/isrune"
---

# isrune(3)

valid character test

## NAME

**isrune** – valid character test

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

**#include \<ctype.h\>**

*int*\

**isrune**(*int c*);

## DESCRIPTION

The **isrune**() function tests for any character that is valid in the current character set. In the ASCII character set, this is equivalent to **isascii**().

## RETURN VALUES

The **isrune**() function returns zero if the character tests false and returns non-zero if the character tests true.

## SEE ALSO

[ctype(3)](/ctype/3.md), [isascii(3)](/isascii/3.md), [iswrune(3)](/iswrune/3.md), [ascii(7)](/ascii/7.md), isalnum\_l

## HISTORY

The **isrune**() function appeared in 4.4BSD.