an unset var == zero?

[Anon]

I am completely baffled by this, and it makes no sense to me -

I have a user input variable, where a numerical zero is an important imput, while no input is equally as important, but means infinity, basically -
(enter value above which free shipping is available - zero=free ship on all; null=no free ship on anything)

so my code to echo the entered value is:
<?php
if ($ins_free_ship==0) {
echo"Free shipping available on all products</td>";
}else if (!$ins_free_ship) {
echo"No free shipping available</td>";
}else{
echo "free shipping on products \$".$ins_free_ship." and above</td>";
}
?>

If any value >0 is entered, everything is fine, but a zero or NULL value echos "Free shipping available on all products".

Huh?

!isset($ins_free_ship) has the same effect

[Anon]

i sorted it (still don't understand why php would equate NULL to zero)

shuffle the order of 'if' and check strlen()

if (strlen($var)=='') {
echo "value unset";
}else if ($var==0) {
echo "zero";
}else{
echo $var;
}

just for those who stumble upon this problem in the future
;-)

[Anon]

Try $var === 0 instead of $var == 0;

PHP is probably doing a type conversion on your $var, so it can compare like types. Zero-length string equates to integer 0.