PHP string comparison using '=='

Question

I did a few tests with strings using '=='. I know to compare string '==' is not the way, but there is a weird behavior I want to solve.

I'm following the PHP documentation in this page: http://www.php.net/manual/en/language.operators.comparison.php . This is the test I did

<?php 
   var_dump( "100" == "1e2" ); //outputs boolean true
   var_dump( (int) "100" ); //int 100
   var_dump( (int) "1e2" ); //int 1
?> 

The documentation says when we compare strings with numbers, PHP first converts the string to numbers, but when I convert '100' and '1e2' to numbers they are not equal. The comparison should outputs boolean false.

Why is this weird behavior? Thanks!

Answer 1

Not all numbers are integers. 1e2 is a float (that happens to be representable as an integer, but is not directly convertible to an integer). Try converting to floats rather than ints:

<?php 
   var_dump( "100" == "1e2" ); // bool(true)
   var_dump( (float) "100" );  // float(100)
   var_dump( (float) "1e2" );  // float(100)
?>