what is difference

[jansky]

to all guru

what is difference between
if ($var=="")

and
if (empty($var))

thanks

[NogDog]

In that circumstance, the only difference is that the first one will throw a notice-level warning if the variable is not set at all, whereas the second one will not.

[Piranha]

From the manual

Return Values

Returns FALSE if var has a non-empty and non-zero value.

The following things are considered to be empty:

* "" (an empty string)
* 0 (0 as an integer)
* "0" (0 as a string)
* NULL
* FALSE
* array() (an empty array)
* var $var; (a variable declared, but without a value in a class)

In other words, it will be regarded as empty with other values than an empty string, making those two ways totally different.

[NogDog]

Piranha;10878205 wrote:

From the manual

In other words, it will be regarded as empty with other values than an empty string, making those two ways totally different.

That would be correct if using the "===" operator, but the "==" does the same loose-typing conversion of 0/empty/false values.

<pre><?php
$testData = array(0, "0", "", false, null, 'only "true" value');
for($ix = 0; $ix < count($testData); $ix++)
{
   echo "\nTest $ix\n";
   var_dump($testData[$ix]);
   echo "empty(): ";
   $result = empty($testData[$ix]);
   var_dump($result);
   echo "==     : ";
   $result = ($testData[$ix] == '');
   var_dump($result);
   echo "===    : ";
   $result = ($testData[$ix] === '');
   var_dump($result);
}
?></pre>

Results:

Test 0
int(0)
empty(): bool(true)
==     : bool(true)
===    : bool(false)

Test 1
string(1) "0"
empty(): bool(true)
==     : bool(false)
===    : bool(false)

Test 2
string(0) ""
empty(): bool(true)
==     : bool(true)
===    : bool(true)

Test 3
bool(false)
empty(): bool(true)
==     : bool(true)
===    : bool(false)

Test 4
NULL
empty(): bool(true)
==     : bool(true)
===    : bool(false)

Test 5
string(17) "only "true" value"
empty(): bool(false)
==     : bool(false)
===    : bool(false)

[Piranha]

Thanks for correcting me NogDog, I didn't know what the difference between == and === was.

However there was one difference, and that is the string "0".

I'll gladly admit that the difference between using empty and == is not nearly as big as I thought, but it seems that there is a difference in the result (other than the warning).

[NogDog]

Yeah, I generally avoid empty() unless it's obviously applicable to the situation in hand. I generally prefer something like:

if(isset($_POST['var']) and trim($_POST['var']) !== '')
{
   // good to go
}
else
{
   // empty, try again
}