What will be the output of the following PHP code ?

<?php
$i = 0;
for ($i)
{
    print $i;
}
?>

<?php
$x;
if ($x)
    print "hi" ;
else
    print "how are u";
?>

<?php
$x = 0;
if ($x++)
    print "hi";
else
    print "how are u";
?>

<?php
$x;
if ($x == 0)
    print "hi" ;
else
    print "how are u";
    print "hello"
?>

<?php
$x = 0;
if ($x == 1)
    if ($x >= 0)
	print "true";
    else
	print "false"; 
?>