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

# towlower(3)

upper case to lower case letter conversion (wide character version)

## NAME

**towlower**, **towlower\_l** – upper case to lower case letter conversion (wide character version)

## LIBRARY

Standard C Library (libc, -lc)

## SYNOPSIS

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

*wint\_t*\

**towlower**(*wint\_t wc*);

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

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

*wint\_t*\

**towlower\_l**(*wint\_t wc*, *locale\_t loc*);

## DESCRIPTION

The **towlower**() function converts an upper-case letter to the corresponding lower-case letter.

Although the **towlower**() function uses the current locale, the **towlower\_l**() function may be passed a locale directly. See [xlocale(3)](/xlocale/3.md) for more information.

## RETURN VALUES

If the argument is an upper-case letter, the **towlower**() function returns the corresponding lower-case letter if there is one; otherwise, the argument is returned unchanged.

## SEE ALSO

[iswlower(3)](/iswlower/3.md), [tolower(3)](/tolower/3.md), [towupper(3)](/towupper/3.md), [wctrans(3)](/wctrans/3.md), [xlocale(3)](/xlocale/3.md)

## STANDARDS

The **towlower**() function conforms to ISO/IEC 9899:1999 (“ISO C99”).