---
name: "al_ustr_prev"
section: "3alleg5"
platform: "linux"
package: "allegro5-doc"
version: "2:5.2.10.1+dfsg-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/al_ustr_prev/3alleg5"
---

# al\_ustr\_prev(3alleg5)

Allegro 5 API

## NAME

al\_ustr\_prev - Allegro 5 API

## SYNOPSIS

-

  ```
  #include <allegro5/allegro.h>
  bool al_ustr_prev(const ALLEGRO_USTR *us, int *pos)
  ```

## DESCRIPTION

Find the byte offset of the previous code point in string, before `*pos`. `*pos` does not have to be at the beginning of a code point. Returns true on success, and the value pointed to by `pos` will be updated to the found offset. Otherwise returns false if `*pos` was already at the end of the string, and `*pos` is unmodified.

This function just looks for an appropriate byte; it doesn’t check if found offset is the beginning of a valid code point. If you are working with possibly invalid UTF-8 strings then it could skip over some invalid bytes.

## SEE ALSO

al\_ustr\_next(3alleg5)