The use of PHP global variables and local variables

<?PHP//Error handler function$v 1=10;functionF1 () {//This is a global variable that changes the local to a global variable, that is, to create a local variable with the same name as the outside and to point to it by means of a "reference."Global $v 1;Echo"V1=$v 1";$v 1++;unset($v 1);//Break LinkEcho"The local V1 is$v 1";Echo"<br>";$GLOBALS[' V2 ']=100;//becomes Super global variable//If the disconnection is not//unset ($GLOBALS [' v2 ']);}f1 ();Echo"The external v1 is$v 1";Echo"<br>";Echo"The External v2 is$v 2";?>

The use of PHP global variables and local variables