---
name: "SDL_utf8strnlen"
section: "3"
platform: "linux"
package: "libsdl3-doc"
version: "3.2.10+ds-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/SDL_utf8strnlen"
---

# SDL\_utf8strnlen(3)

Count the number of codepoints in a UTF-8 string, up to n bytes.

## NAME

SDL\_utf8strnlen - Count the number of codepoints in a UTF-8 string, up to n bytes.

## HEADER FILE

Defined in SDL3/SDL\_stdinc.h

## SYNOPSIS

```
#include "SDL3/SDL.h"
```

**size\_t SDL\_utf8strnlen(const char \*str, size\_t bytes);**

## DESCRIPTION

Counts the \_codepoints\_, not \_bytes\_, in **str** , excluding the null terminator.

If you need to count the bytes in a string instead, consider using

**SDL\_strnlen** ().

The counting stops at **bytes** bytes (not codepoints!). This seems counterintuitive, but makes it easy to express the total size of the string's buffer.

Since this handles Unicode, it expects the strings to be well-formed UTF-8 and not a null-terminated string of arbitrary bytes. Bytes that are not valid UTF-8 are treated as Unicode character U+FFFD (REPLACEMENT CHARACTER), so a malformed or incomplete UTF-8 sequence might increase the count by several replacement characters.

## FUNCTION PARAMETERS

- *str*

  The null-terminated UTF-8 string to read. Must not be NULL.

- *bytes*

  The maximum amount of bytes to count.

## RETURN VALUE

Returns The length (in codepoints, excluding the null terminator) of **src** but never more than **maxlen** .

## THREAD SAFETY

It is safe to call this function from any thread.

## AVAILABILITY

This function is available since SDL 3.2.0.

## SEE ALSO

**•**(3), [**SDL\_utf8strlen**(3)](/SDL_utf8strlen/3.md), **•**(3), [**SDL\_strnlen**(3)](/SDL_strnlen/3.md)