Try catch statements in PHP

Question

Hey everyone, Im quite new to programming so please be nice :)

I am currently experimenting with try-catch statements, I read the documentation on the php.net website and didn't find it all that helpful. I understand what they do, but from reading it, i would not be able to implement one into my own code. I need a real example to help me understand.

How could i turn this example into a try catch statement, if the upload was not successful.

    $move = move_uploaded_file($_FILES['file']['tmp_name'], $_SERVER['DOCUMENT_ROOT']."/uploads/".$_FILES['file']['name']);

 if (!$move) {
  die ('File Didnt Upload');
 } else {   
  //opens the uploaded file for extraction
  echo "Upload Complete!";
 }

This may not be a good example to work with, but any help would be appreciated :)

Thanks alot!

Answer 1

You could do it like this.

try {
    //throw exception if can't move the file
    if (!move_uploaded_file( ... )) {
        throw new Exception('Could not move file');
    }

    //do some more things with the file which may also throw an exception
    //...

    //ok if got here
    echo "Upload Complete!";
} catch (Exception $e) {
    die ('File did not upload: ' . $e->getMessage());
}

It is a bit pointless for the above example, but you should get the idea. Note that you can throw the exception(s) from anywhere (e.g. within a function/method that you call from withing the try{}) and they will propagate upwards.

Answer 2

Well, if you want to use exceptions, you could do something like:

function handleUpload() {


    $move = move_uploaded_file($_FILES['file']['tmp_name'], $_SERVER['DOCUMENT_ROOT']."/uploads/".$_FILES['file']['name']);

    if (!$move) {
       throw new Exception('File Didnt Upload');
    }

}

try {
   handleUpload();
   echo "File Uploaded Successfully";
} catch(Exception $ex) {
   die($ex->getMessage);
}

I know this may seem like bloat - but you can call the method from anywhere in the call stack, and catch the exception at any point.

Answer 3

try-catch statements are used to handle exceptions. I don't believe that the funtion move_uploaded_files can throw and exception, as such I think that you code is written is correct. After the call, you look at the return code. If it's false, you end processing, otherwise you are report success.

Answer 4

According to a similar post in PHPbug, only OO code (Object-Oriented code) throws exceptions. That would mean that functions such as move_uploaded_file won't throw their own exceptions, but some other code will.