<?php

$not_an_int = "sa';';';'sd12340asd";
$actual_int = "12341234";

# sanitization
var_dump(filter_var($not_an_int, FILTER_SANITIZE_NUMBER_INT));
var_dump(filter_var($actual_int, FILTER_SANITIZE_NUMBER_INT));

# validation
var_dump(filter_var($not_an_int, FILTER_VALIDATE_INT));
var_dump(filter_var($actual_int, FILTER_VALIDATE_INT));