$value = '0';
 
    // Here's how PHP works with the normal comparison operator:
    if ( $value )
    {
        // Since the $value is 0, PHP interprets it as false. However since 
        // this is a non-empty string one might expect it to be true.
        print "if ( {$value} )\n";
    }
 
    if ( $value == false )
    {
        // PHP automatically converts strings to numbers when it things it 
        // needs to. This can cause problems because you may have wanted to
        // check for a boolean, not a string.
        print "if ( {$value} == false )\n";
    }
 
    if ( $value == true )
    {
        // Since the value is both a string and numericaly 0, this evaluates
        // to false. I don't think there is any time when you would want it to
        // be true. Thankfully PHP doesn't think so either.
        print "if ( {$value} == true )\n";
    }
 
    if ( $value == 0 )
    {
        // PHP will convert the value to the type you are comparing before
        // comparison. This may not be intented. However this evaluates
        // to true.
        print "if ( {$value} == 0 )\n";
    }
 
    if ( $value == '0' )
    {
        // Since the value matches, this evaluates to true
        print "if ( {$value} == '0' )\n";
    }
 
    // Now we try the === operator:
    if ( $value === 0 )
    {
        // Since the type of the value is not a number, this evaluates to false.
        print "if ( {$value} === 0 )\n";
    }
 
    if ( $value === '0' )
    {
        // Since type _and_ value matches this evaluates to true.
        print "if ( {$value} === '0' )\n";
    }
 
    // Some alternative ways to compare:
    if ( (int) $value === 0 )
    {
        // Since we typecast to an int, this works.
        print "if ( (int) {$value} === 0 )\n";
    }
 
    if ( intval($value) === 0 )
    {
        // Intval takes the integer value of any string
        print "if ( intval({$value}) === 0 )\n";
    }
 
    if ( (string) $value === '0' )
    {
        print "if ( (string) {$value} === '0' )\n";
    }
 
    /*
    The above outputs:
 
 
    if ( 0 == false )
    if ( 0 == 0 )
    if ( 0 == '0' )
    if ( 0 === '0' )
    if ( (int) 0 === 0 )
    if ( intval(0) === 0 )
    if ( (string) 0 === '0' )
    */