---
name: "SDL_strnstr"
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_strnstr"
---

# SDL\_strnstr(3)

Search a string, up to n bytes, for the first instance of a specific substring.

## NAME

SDL\_strnstr - Search a string, up to n bytes, for the first instance of a specific substring.

## HEADER FILE

Defined in SDL3/SDL\_stdinc.h

## SYNOPSIS

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

**char \* SDL\_strnstr(const char \*haystack, const char \*needle, size\_t maxlen);**

## DESCRIPTION

The search ends once it finds the requested substring, or a null terminator byte to end the string, or **maxlen** bytes have been examined. It is possible to use this function on a string without a null terminator.

Note that this looks for strings of \_bytes\_, not \_characters\_, so it's legal to search for malformed and incomplete UTF-8 sequences.

## FUNCTION PARAMETERS

- *haystack*

  the string to search. Must not be NULL.

- *needle*

  the string to search for. Must not be NULL.

- *maxlen*

  the maximum number of bytes to search in **haystack** .

## RETURN VALUE

Returns a pointer to the first instance of **needle** in the string, or NULL if not found.

## THREAD SAFETY

It is safe to call this function from any thread.

## AVAILABILITY

This function is available since SDL 3.2.0.