Difference btw these 2

[quelle]

Actually what's the difference between

if(...)

and

if(isset(...)

[Maq]

isset - Determine if a variable is set and is not NULL.

if - If expression evaluates to TRUE, PHP will execute statement, and if it evaluates to FALSE - it'll ignore it.

 

More detailed explanation in the manual links above.

[quelle]

what actually does it mean NULL and look at this, for example i could take a variable from a form on both ways

if($_POST['name']) {

is same like this ?

if(isset($_POST['name'])) {

[spiderwell]

the first example will throw an error saying name is undefined if it wasnt found in the $_POST array, that is Null

 

isset is a way of being sure something exists before retreiving its value

 

i usually retreive all my form values like this

 

if (isset($_POST['name'])) $name = $_POST['name'];

[quelle]

but what if $_POST['name'] actually exists, whats the difference then ? if($_POST... would have returned the same as isset

[spiderwell]

yes you would get the same thing at the end.

 

its a technique to prevent errors in your code with undefined variables.

its down to personal preference, but really its better to catch potential errors than not, even if you know that $_POST is going to be there.

 

you dont have to do it, just like you dont have to do many things in code, but in a professional environment, it would be expected to write code that is covering any possible errors that might be thrown.

 

[maxudaskin]

if is not a function. It's merely an operator (correct me if I'm using the wrong terms).

isset is a function. It checks if the variable that you are looking for actually exists in memory and returns true if it is, false if it isn't.

empty is a function. It checks if the variable is in memory and if it's not NULL, '' or whatever it will juggle as an empty variable. It returns false if one of those conditions are false.

 

I suggest that you do some reading of these PHP tutorials on W3Schools.

[spiderwell]

only dont go to w3schools as they are not at all associated with w3c and are often giving out incorrect information.

 

but thats a whole different story altogether