Global variables in PHP [duplicate]

Question

I'm writing a script that will select a random word from among words in an input file, multiple times. Now calling file() multiple times seems inefficient, so I'm thinking of having a global array for the words from the file and a function that will load the file into the array (called before selecting random words). Why doesn't it work?

global $words;

function init_words($file)
{
    $words = file($file);
    $count = count($words);
    echo "$count words<br>\n"; // "3 words"
}

init_words("/foo/bar");
$count = count($words);
echo "$count words<br>\n"; // "0 words" 

Answer 1

You need to declare $words global within the function itself. See:

$words = '';

function init_words($file)
{
    global $words;
    $words = file($file);
    $count = count($words);
    echo "$count words<br>\n"; // "3 words"
}

I suggest you review the variable scope chapter in the PHP manual.

As an aside I would never write this code in this way. Avoid globals unless they are absolutely necessary.

I would write your code this way to avoid this problem:

function init_words($file)
{
    $words = file($file);
    $count = count($words);
    echo "$count words<br>\n"; // "3 words"
    return $words;
}

$words = init_words("/foo/bar");
$count = count($words);
echo "$count words<br>\n"; // "3 words" 

Please see the returning values chapter in the PHP manual for more information on this.