Comment Added by : Bijan

Comment Added at : 2012-09-21 20:49:41

Comment on Tutorial : isset() function in PHP By Emiley J.
The !isset() is basically checking if the string is NOT true.
Take the first example:
if (isset($first_name)) {

print '$first_name is set';

}
This checks if the var $first_name has been declared. In plain English, if user hasn't filled out the form "First Name" yet then it will return false when he submit it.
Now:
if (!isset($first_name)) {

//So the $first_name is not set obviously, not you want to notify the user that he must
//have it filled

print 'Please fill out your First Name';

}
For this one you are checking if the $first_name has NOT been declared. The "!" means "NOT", this is listed in the operators http://www.w3schools.com/php/php_operators.asp
There are two or more ways to do this and it depends on what your are tying to achieve.
I am not a "PRO" at php just yet since I just stated but you'll know this but reading the link I gave.Also please if I said something wrong please correct me. ^_^

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