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difference between if($value) and if(isset($value))

Posted: Wed Aug 19, 2009 3:43 am
by corecoder
Hi all,

what is the difference between difference between if($value) and if(isset($value)). both returns true is value is exists. which the best one to use ?

Re: difference between if($value) and if(isset($value))

Posted: Wed Aug 19, 2009 4:00 am
by Mark Baker
corecoder wrote:what is the difference between difference between if($value) and if(isset($value)). both returns true is value is exists. which the best one to use ?
Try

Code: Select all

 
echo '<b>Test 1, $value not set</b>';
echo '<br />';
if($value) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
if(isset($value)) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
 
$value = 9;
echo '<b>Test 2, $value is numeric 9</b>';
echo '<br />';
if($value) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
if(isset($value)) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
 
$value = 0;
echo '<b>Test 3, $value is numeric 0</b>';
echo '<br />';
if($value) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
if(isset($value)) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
 
$value = False;
echo '<b>Test 4, $value is boolean false</b>';
echo '<br />';
if($value) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
if(isset($value)) { echo '$value is true'; } else {echo '$value is false'; }
 
and see what the differences are

Re: difference between if($value) and if(isset($value))

Posted: Wed Aug 19, 2009 4:16 am
by jazz090
if(value) checks if value is (bool) TRUE whilst isset does what its supposed to. always use the latter for checking if a var is declared.

Re: difference between if($value) and if(isset($value))

Posted: Wed Aug 19, 2009 5:32 am
by corecoder
Mark Baker wrote:
corecoder wrote:what is the difference between difference between if($value) and if(isset($value)). both returns true is value is exists. which the best one to use ?
Try

Code: Select all

 
echo '<b>Test 1, $value not set</b>';
echo '<br />';
if($value) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
if(isset($value)) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
 
$value = 9;
echo '<b>Test 2, $value is numeric 9</b>';
echo '<br />';
if($value) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
if(isset($value)) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
 
$value = 0;
echo '<b>Test 3, $value is numeric 0</b>';
echo '<br />';
if($value) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
if(isset($value)) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
 
$value = False;
echo '<b>Test 4, $value is boolean false</b>';
echo '<br />';
if($value) { echo '$value is true'; } else {echo '$value is false'; }
echo '<br />';
if(isset($value)) { echo '$value is true'; } else {echo '$value is false'; }
 
and see what the differences are
thanks buddy
any idea about this question viewtopic.php?f=1&t=104684