PHP: working with functions storing array

I have a

function displayErr(){
    $err[] = "You have an error";
}

later in my code

if($bla==false) { displayErr(); }
if(!empty($err)) { echo print_r($err); }

I don't get anything, can't I call a function that adds on 开发者_Go百科$err and then check it later?

The variable $err is is only visible within the function displayErr(). What you want is to access a global variable within the function. To do this, you need to import it using the global keyword, as the following example shows:

function displayErr(){
    global $err;
    $err[] = "You have an error";
}

For more information regarding variable scope, see this link: http://php.net/manual/en/language.variables.scope.php

$err is only visible in the scope of your displayErr() function. You need to pass it, or its values, around. A couple of options:

1. Return the error message and append to $err within the calling scope

   function displayErr() {
       return "You have an error";
   }
   
   $err = array();
   if($bla==false) { $err[] = displayErr(); }
   if(!empty($err)) { print_r($err); }
   

2. Use global

   function displayErr() {
       global $err;
       $err[] = "You have an error";
   }
   
   $err = array();
   if($bla==false) { displayErr(); }
   if(!empty($err)) { print_r($err); }
   

Also, print_r() outputs stuff by itself, you don't need to echo print_r().

You can use the global keyword to store your variable as global:

function displayErr()
{ 
global $err;
$err = "You have an error"; 
}

[...]

global $err;
if($bla==false) { displayErr(); } if(!empty($err)) { echo print_r($err); }

$err is only available in your displayErr function.

You need to add a global statement. Like this: displayErr() {global $err; ... }

This is called variable scoping, and you can read more about it here.

A simple error handling class example:

class ErrorHandler()
{
    private $errors = array();

    public function add_error($error = 'You have an error')
    {
        $this->errors[] = $error;
    }

    public function get_errors()
    {
        return $this->errors;
    }

    public function print_errors()
    {
        print_r($this->errors);
    }
}

$errorhandler = new ErrorHandler;
if($bla==false) $errorhandler->add_error('Variable bla is not set!');
if($bla=='unknown error') $errorhandler->add_error();

$errors = $errorhandler->get_errors();
if($errors) print_r($errors); // or
if($errors) $errorhandler->print_errors();