Help with image upload script - need to make an if null statement

[norbie]

Hi guys,

I made/used an image uploader script today.

This is how the code works now after POSTing the details with a form.

PHP Code:

if (isset($_FILES['new_image'])){

// do image stuff

} else {

// don't do image stuff

} 


Basically the image script does work but if the user doesn't enter anything into the image box, the rest of the form functions will work (entering info into a database) but it has messy errors on the page.

How can I create some kind of if statement that says "if they havent entered anything into the image field then dont do stuff" ?

I tried echoing $_FILES['new_image'] but it comes back as "array". I have not used $_FILES before so do not understand this.

Thanks.

[John]

$_FILES is a global multi-dimensional array defined by php. If you would like to see the contents of the array you can use the print_r() function.

PHP Code:

print_r($_FILES['new_image']); 


To access an element in the array, you need to ask for its exact index. For example

PHP Code:

echo $_FILES['new_image']['name']; 


will echo the name of the file. See here for more information: PHP: Handling file uploads - Manual

I've written a upload class that you can modify if you would like: PHP: Upload Class

[norbie]

Ah I see. Thanks John.

The upload script all works now apart from this null issue so I'd rather not change it with a different system now but will look at yours.

Is there a way I can add an "if null" check?

[norbie]

All sorted now, I just used:

PHP Code:

if ($_FILES['new_image']['name'] == "") { 


Thanks

[phpforfun]

cant you use

if (empty($_FILES['new_image']['name'])){

[Xav]

There are usually different ways to accomplish a task. In some circumstances, "" is not the same as null, so you need to be careful which one you use.

[John]

Originally Posted by Xav

In some circumstances, "" is not the same as null, so you need to be careful which one you use.

That is 100% true. From my experience with working $_GET, $_POST, or $_FILE they all seem to turn up different results. Often times !isset($var), $empty($var), $var == null, $var == "", and $var == " " will often turn up different results.

[Xav]

100% true? Wow, this must be a first!

Say you have a variable:

PHP Code:

$var 


If you don't assign any value to it, the variable has not been instantiated yet. Therefore, it contains no value at all - in other words, it's null.

However, if you use:

PHP Code:

$var = ""; 


A value is being passed into the variable. Even though it's got a length of 0, it's still a string value - just a blank one. Therefore, the variable is now not null, as it contains a value (albeit a blank one).

Finally, if we pass a space to the variable:

PHP Code:

$var = " "; 


Here, the value passed has a length of 1 - in programming, a space is considered as just another ASCII character, just like a letter or number. Therefore, this variable is also not null, as it holds a normal value - the only difference is, the value isn't visible to humans, as it's used to fill a gap.