# imap_uid

(PHP 4, PHP 5, PHP 7, PHP 8)

imap_uid — This function returns the UID for the given message sequence number

### Descripción

imap_uid(IMAP\Connection `$imap`, int `$message_num`): int|false

This function returns the UID for the given message sequence number. An UID is a unique identifier that will not change over time while a message sequence number may change whenever the content of the mailbox changes.

This function is the inverse of imap_msgno().

### Parámetros

`imap`

  An IMAP\Connection instance.

`message_num`

  The message number.

### Valores devueltos

The UID of the given message.

### Historial de cambios

Versión | Descripción
--- | ---
8.1.0 | The `imap` parameter expects an IMAP\Connection instance now; previously, a valid `imap` recurso was expected.

### Notas

> Nota:

> This function is not supported by POP3 mailboxes.

### Ver también

- imap_msgno() - Gets the message sequence number for the given UID