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function is not described

_wp_get_post_revision_version() WP 3.6.0

Gets the post revision version.

This is an internal function for using it by WP core itself. It's not recommended to use this function in your code.

No Hooks.

Return

Int|false. Null. Nothing.

Usage

_wp_get_post_revision_version( $revision );
$revision(WP_Post) (required)
-

Changelog

Since 3.6.0 Introduced.

Code of _wp_get_post_revision_version() WP 5.7

<?php
function _wp_get_post_revision_version( $revision ) {
	if ( is_object( $revision ) ) {
		$revision = get_object_vars( $revision );
	} elseif ( ! is_array( $revision ) ) {
		return false;
	}

	if ( preg_match( '/^\d+-(?:autosave|revision)-v(\d+)$/', $revision['post_name'], $matches ) ) {
		return (int) $matches[1];
	}

	return 0;
}