how validate if is the last day of the month in php code example

Example 1: php check if day in month

// function
cal_days_in_month(calendar,month,year);
//e.g.
$d=cal_days_in_month(CAL_GREGORIAN,10,2005);
echo "There was $d days in October 2005";

Example 2: check if is the last day of the month php

if(gmdate('t') == gmdate('d')){
    echo 'Last day of the month.';
}