The value false is not a constant for the number 0, it is a boolean value that indicates false. The value true is also not a constant for 1, it is a special boolean value that indicates true. It just happens to cast to integer 1 when you print it or use it in an expression, but it's not the same as a constant for the integer value 1 and you shouldn't use it as one. But there may be times when it might be helpful to see the value of the Boolean as a 1 or 0. Here's how to do it.
<?php
$var1 = TRUE;
$var2 = FALSE;
echo $var1; // Will display the number 1
echo $var2; //Will display nothing
/* To get it to display the number 0 for
a false value you have to typecast it: */
echo (int)$var2; //This will display the number 0 for false.
var_dump($var1); //bool(true)
var_dump($var2); //bool(false)
?>
References:
Bool
var_dump