- is_numeric: documentation ( source)
<?php
$target=13;
$try=(isset($_POST['number'])) ? $try+1 : 1;
if(!isset($_POST['guess'])){
$message="welcome to geuss machine";}
elseif(!is_numeric($_POST['guess'])){
$message="inpute is unidentify";}
elseif($_POST['guess']<$target){
$message="it's to small!";}
elseif($_POST['guess']>$target){
$message="it's to big!";}
elseif($_POST['guess']=$target){
$message="you win number was:$target";}
else
$message="it's confusing!";
?>