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@NogDogJan 12.2013 — #Because of PHP's loose typing, where it's casting 'x' to integer so that it can compare both expressions as the same type, and [b](int) 'x'[/b] will evaluate to 0. If you don't want that loose typing, then use the "===" (is identical to) operator, which checks for both same type and value, instead of the "==" operator.
@NogDogJan 13.2013 — #For info on all the type-juggling possibilities, see http://php.net/manual/en/types.comparisons.php
In your first example, anything that can be considered a zero (0, 0.0, "0", NULL, FALSE, "") will be cast to float as 0.0, so if $a is FALSE and $b is "", then they would both be cast to 0.0 and the comparison would be true -- which may or may not be what you want to happen. If you want to make sure you are comparing numbers, you might want to test each value with is_numeric() first, and if either test fails throw an exception or whatever other error-handling you want to do.
Or you could insist that those variables be floats (or whatever), and test them accordingly with is_float(), etc; But I don't think there's a one size fits all solution, since many times loose typing and type-juggling works fine.
If it becomes really critical, you could even create classes for specific types, which you could then pass into function parameters with type-hinting.
That's likely overkill for most applications, but something along that lines might be quite useful when you really need to keep your variable types in order.
What does the variable actually contain?
Hello,
I have no idea why these scripts echo “ex” instead of “zero”. Seems straight forward but it’s got me stumped. Any ideas?
[code=php]
$ws=0;
echo $ws.’,’.($ws==’x’?’ex’:’zero’);
exit;
I would expect to see:
0,zero
But instead, it shows:
0,ex
Or…
[code=php]
$ws=0;
$ws=($ws==’x’?’ex’:’zero’);
echo $ws;
exit;
I would expect it to echo “zero”, but it echos “ex”
Any ideas why this is? Incidentally, it doesn’t matter what string I use (or even if I use $ws==0), it consistently displays “ex”.
I appreciate any ideas.
Thanks.
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@NogDogJan 12.2013 — #Because of PHP's loose typing, where it's casting 'x' to integer so that it can compare both expressions as the same type, and [code=php]
<?php
$result = (0 == 'x');
var_dump($result); // true
echo "<br />n";
$result = (0 === 'x');
var_dump($result); // false
echo "<br />n";
$result = (0 === '0');
var_dump($result); // false
echo "<br />n";
$result = (0 == '1x');
var_dump($result); // false ('1x' will cast to 1)
[/code]0
@NogDogJan 13.2013 — #For info on all the type-juggling possibilities, see In your first example, anything that can be considered a zero (0, 0.0, "0", NULL, FALSE, "") will be cast to float as 0.0, so if $a is FALSE and $b is "", then they would both be cast to 0.0 and the comparison would be true -- which may or may not be what you want to happen. If you want to make sure you are comparing numbers, you might want to test each value with is_numeric() first, and if either test fails throw an exception or whatever other error-handling you want to do.
Or you could insist that those variables be floats (or whatever), and test them accordingly with is_float(), etc; But I don't think there's a one size fits all solution, since many times loose typing and type-juggling works fine.
If it becomes really critical, you could even create classes for specific types, which you could then pass into function parameters with type-hinting.
[code=php]
<?php
abstract class Type
{
private $value;
public function __construct($value=null)
{
if($value !== null) {
$this->set($value);
}
}
public abstract function set($value);
public function get()
{
return $this->value;
}
}
class FloatType extends Type
{
public function set($value)
{
if( ! is_numeric($value)) {
throw new Exception ("'$value' is not numeric");
}
$this->value = (float)$value;
}
}
function foo(FloatType $bar)
{
$result = $bar->value . " is " . (is_float($bar->value) ? '' : 'not ') . "a float";
return $result;
}
// actually do something now:
$test = 1.234;
echo foo(new FloatType($test));
echo "<br />n";
$test2 = '12nope';
echo foo(new FloatType($test2)); // throws exception
[/code]That's likely overkill for most applications, but something along that lines might be quite useful when you really need to keep your variable types in order.