当包含一个使用php函数的文件不起作用？

Question

MY PHP FUNCTION IS

function functionName()
{
include($_SERVER['DOCUMENT_ROOT']."/path/file.php");
}

Content of File.php is

$foo = 'bar';

Calling function (content of file test.php)

functionName();

When call function and variable not work

echo $foo;  <- not works

But when adding code below its works (content of file test.php)

include($_SERVER['DOCUMENT_ROOT']."/path/file.php");
echo $foo; <- its works

Answer 1

function functionName()
{
global $foo;
global $bar;

include($_SERVER['DOCUMENT_ROOT']."/path/file.php");
}
functionName();
echo $foo;
echo $bar;