PHP语法问题：global $ argv，$ argc;

Question

So I have a PHPUnit test, and found this code within a function.

global $argv, $argc;
echo $argc;
print_r($argv);

I understand what these variables represent (arguments passed from the command line), but I've never seen this syntax before:global $argv, $argc;

What specifically is going on here?

Answer 1

The global keyword tells PHP to use the global scope version of a variable and make it visible to the current scope as well, so that variables declared outside functions/classes can be accessed within them too.

Otherwise, trying to read/assign those variables would operate on a different local version of them instead.

Compare:

$foo = 1;

function test() {
    $foo = 2;
}

echo $foo; // prints 1

versus...

$foo = 1;

function test() {
    global $foo;
    $foo = 2;
}

echo $foo; // prints 2