<?php
$input_string = "yes today is 2013-10-24";
if(preg_match("/\d{4}-\d{2}-\d{2}/", $input_string, $match)) {
}
else
echo "not matched";
PD9waHAKCiAgICAkaW5wdXRfc3RyaW5nID0gInllcyB0b2RheSBpcyAyMDEzLTEwLTI0IjsKICAgIGlmKHByZWdfbWF0Y2goIi9cZHs0fS1cZHsyfS1cZHsyfS8iLCAkaW5wdXRfc3RyaW5nLCAkbWF0Y2gpKQogICAgewogICAgCXByaW50X3IoJG1hdGNoKTsKICAgIH0KICAgIGVsc2UKICAgIAllY2hvICJub3QgbWF0Y2hlZCI7