PHP try-catch not working [duplicate]

Question

try     
{
    $matrix = Query::take("SELECT moo"); //this makes 0 sense

    while($row = mysqli_fetch_array($matrix, MYSQL_BOTH)) //and thus this line should be an error
    {

    }

    return 'something';
}
catch(Exception $e)
{
    return 'nothing';   
}

However instead of just going to catch part and returning nothing it shows a warning Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, null given in the line starting with while. I have never came up to using exceptions in php, but used them a lot in C# and it seems in PHP they are working differently or, as always, I am missing something obvious.

Here are some like your question: stackoverflow.com/questions/1241728/can-i-try-catch-a-warning — Estefano Salazar
– Estefano Salazar, Commented Sep 11, 2012 at 20:53
@SirDarius - Interesting and worthwhile reading link. Thanks :) — Andrius Naruševičius
– Andrius Naruševičius, Commented Sep 11, 2012 at 20:58

Jeff · Accepted Answer · 2015-05-08 20:41:45Z

44

You can't handle Warnings/Errors with try-catch blocks, because they aren't exceptions. If you want to handle warnings/errors, you have to register your own error handler with set_error_handler.

But it's better to fix this issue, because you could prevent it.

edited May 8, 2015 at 20:41

Jeff

14.3k12 gold badges61 silver badges107 bronze badges

answered Sep 11, 2012 at 20:54

Philipp

15.7k4 gold badges38 silver badges54 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Mike Brant Over a year ago

building on this answer, you could easily set set_error_handler to capture PHP errors and issue an Exception, at which point your try-catch will work. I am sure you can Google for something suitable.

oxygen Over a year ago

For throwing exceptions, set_error_handler should be used in combination with ErrorException (built-in class specifically for this use).

Captain Hypertext Over a year ago

I've been doing php full time for a few years now, and I didn't even know this.

John Over a year ago

You can not prevent users from using incorrect authentication credentials via imap_open so no, you can't prevent it.

Gilad Tiram · Accepted Answer · 2018-01-11 07:49:12Z

43

Exception is only subclass of Throwable. To catch error you can try to do one of the following:

try {

    catch (\Exception $e) {
       //do something when exception is thrown
}
catch (\Error $e) {
  //do something when error is thrown
}

OR more inclusive solution

try {

catch (\Exception $e) {
   //do something when exception is thrown
}
catch (\Throwable $e) {
  //do something when Throwable is thrown
}

BTW : Java has similar behaviour.

answered Jan 11, 2018 at 7:49

Gilad Tiram

5494 silver badges5 bronze badges

6 Comments

Shashanth Over a year ago

I used \Exception instead of Exception and it worked. Can you elaborate on how a \ (slash) before Exception makes a huge difference here?

Sandra Over a year ago

@Shashanth using Exception without a slash assumes you've got a use Exception; statement at the top, or aren't using namespacing, the \ makes it look in the global PHP namespace, so it'll catch a PHP Exception and any classes based on it - official documentation: php.net/manual/en/class.exception.php

James John McGuire 'Jahmic' Over a year ago

In modern PHP, with the use of namespaces, the inclusion of the ' \ ' is essential.

w461 Over a year ago

Genius, you saved my day!

Puspam Over a year ago

This should be the accepted answer. Unlike some other languages, PHP has different sets of errors to handle. Fatal errors won't be handled if you only catch the Exception class.

|

datasage · Accepted Answer · 2012-09-11 20:53:26Z

7

In PHP a warning is not an exception. Generally the best practice would be to use defensive coding to make sure the result is what you expect it to be.

answered Sep 11, 2012 at 20:53

datasage

19.7k2 gold badges51 silver badges55 bronze badges

Comments

normmcgarry · Accepted Answer · 2012-09-11 20:55:08Z

4

Welp, unfortunately this is the issue about PHP. Try/catch statements will catch Exceptions, but what you're receiving is an old-school PHP error.

You'll have to catch an error like this with: http://php.net/manual/en/function.set-error-handler.php

Either that or check to see if $matrix is a mysqli_result object prior to performing mysqli_fetch_array.

answered Sep 11, 2012 at 20:55

normmcgarry

6812 gold badges6 silver badges22 bronze badges

1 Comment

Clomp Over a year ago

Old-school PHP error handling worked for me. Thank you for pointing me in that right direction!

adhominem · Accepted Answer · 2012-09-11 20:59:58Z

1

PHP is generating a warning, not an exception. Warnings can't be caught. They are more like compiler warnings in C#.

answered Sep 11, 2012 at 20:59

adhominem

1,16410 silver badges26 bronze badges

Collectives™ on Stack Overflow

PHP try-catch not working [duplicate]

5 Answers 5

4 Comments

6 Comments

Comments

1 Comment

Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

4 Comments

6 Comments

Comments

1 Comment

Comments

Linked

Related