为什么这个功能会失败？

我试图理解为什么这个功能不起作用.有人教育我发生了什么吗？

function API() {
        $seed = str_split(md5(rand(0000000,9999999)));
        $rand = array_rand($seed, 10);
        $convert = array_map(function($n){
            global $seed;
            return $seed[$n];
        },$rand);

        $var1 = implode('',$convert);

        $seed = str_split(md5(rand(0000000,9999999)));
        $rand = array_rand($seed, 10);
        $convert = array_map(function($n){
            global $seed;
            return $seed[$n];
        },$rand);

        $var2 = implode('',$convert);

        $seed = str_split(md5(rand(0000000,9999999)));
        $rand = array_rand($seed, 10);
        $convert = array_map(function($n){
            global $seed;
            return $seed[$n];
        },$rand);

        $var3 = implode('',$convert);
        $NewRecordLocatorID = $var1 . '-' . $var2 . '-' . $var3;
        return $NewRecordLocatorID;
}

此功能仅返回 --

只是回应功能之外的价值？这需要在课堂上吗？

$seed = str_split(md5(rand(0000000,9999999)));
$rand = array_rand($seed, 10);
$convert = array_map(function($n){
    global $seed;
    return $seed[$n];
},$rand);

$var1 = implode('',$convert);

$seed = str_split(md5(rand(0000000,9999999)));
$rand = array_rand($seed, 10);
$convert = array_map(function($n){
    global $seed;
    return $seed[$n];
},$rand);

$var2 = implode('',$convert);

$seed = str_split(md5(rand(0000000,9999999)));
$rand = array_rand($seed, 10);
$convert = array_map(function($n){
    global $seed;
    return $seed[$n];
},$rand);

$var3 = implode('',$convert);
$NewRecordLocatorID = $var1 . '-' . $var2 . '-' . $var3;
echo $NewRecordLocatorID;

以上将返回1d0f09fd36-1e656c979d-3468a68fea所需的结果.

这是因为你打电话的方式global.改变这些:

$convert = array_map(function($n){
    global $seed;
    return $seed[$n];
},$rand);

对此:

$convert = array_map(function($n) use ($seed){
    return $seed[$n];
},$rand);

瞧,它有效.