Boolean help : why does php store true as 1 and false as null??

BigBadKev

Hi all,

How do I get this to pring out "dummy debug = false" ?? or "dummy debug = true" ?? any ideas would be cool as i am going crazy.
If I change "if ($debug == 0) { I still get the same problem...

$myBoolean = false;
$debug = "dummy debug = " . $myBoolean;

newbie($debug);

function newbie($debug) {
  if (is_bool($debug)) {
    if ($debug == false) {
      echo $debug;
    }
    else {
      echo $debug;
    }
  }
  else if (is_string($debug)) {
    echo "is a string";
    echo "<br>";
    echo $debug;
  }
  else {
    echo "is not a boolean";
  }
}
//it prints out.......
//is a string
//dummy debug =

//when i change $myBoolean = true;

//it prints out ......
//is a string
//dummy debug = 1

Thanks in advance.

BBK
🙂

Weedpacket

When you cast false to a string for the purposes of echoing, you get the empty string "" (which isn't the same thing as null) - which would be why you don't see anything. true gets cast to a string that isn't empty - "1", as it happens.

If you cast false and true to integers first, (say, by using (int) or to_integer() or just 0+). Then when you echo the results they (are first cast to strings and then) come out as "0" and "1".

If you want to echo "true" or "false" depending on whether $debug is true or false, then the simplest solution is

echo $debug ? "true" : "false";

BigBadKev

Thanks Weed,

so the string part negates the true or false being printed as it treats both expressions as one big fat string, will this change in php5? I like php but this is really cruel and painful.

p.s big thanks to you and the others who always reply to use newbies, we do appreciate it 🙂

BBK

Weedpacket

Well, I forgot to mention that what you're passing to newbie() - $debug - is a string; one that starts with "dummy debug =". Try passing $myBoolean and see what results you get as to its type.

No; it's not going to change in PHP5 - loose typing and implicit casting are pretty fundamental characteristics of PHP. (without it your code wouldn't even have run, for example).

If you're concerned about the type of variables you're comparing, there are the === and !== comparison operators.

feldon23

True and False are a tad flaky in my experience. Fortunately, the PHP manual tells you when to use certain tests for true or false.