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function is not described

ParagonIE_Sodium_Core_Util::substr() public WP 1.0

Safe substring

{} It's a method of the class: ParagonIE_Sodium_Core_Util{}

No Hooks.

Return

String. Null. Nothing.

Usage

$result = ParagonIE_Sodium_Core_Util::substr( $str, $start, $length );
$str(string) (required)
-
$start(int)
-
$length(int)
-

Code of ParagonIE_Sodium_Core_Util::substr() WP 5.7

<?php
public static function substr($str, $start = 0, $length = null)
{
    /* Type checks: */
    if (!is_string($str)) {
        throw new TypeError('String expected');
    }

    if ($length === 0) {
        return '';
    }

    if (self::isMbStringOverride()) {
        if (PHP_VERSION_ID < 50400 && $length === null) {
            $length = self::strlen($str);
        }
        $sub = (string) mb_substr($str, $start, $length, '8bit');
    } elseif ($length === null) {
        $sub = (string) substr($str, $start);
    } else {
        $sub = (string) substr($str, $start, $length);
    }
    if ($sub !== '') {
        return $sub;
    }
    return '';
}