how to judge a string is eauql 0

$a='ten';

if($a == 0) {

echo 'equal 0';

} else {

       echo 'not equal 0';

}

Now guess echo what?

 

yes ,of course echo 'equal 0 '

 

But why?

 

When use '==', the string $a will be change into a int ,and if $a is not started with char[_/d],it will be 0,so 0==0 is the truth.

 

We can use '===' to judge this .