php = &

$a= 12;$b=&$a;Echo $b;// AEcho"\ n";$b= 23;Echo $a;// atEcho"\ n";$a= 34;Echo $b;// theEcho"\ n";$c= Test ($b);Echo $b;//134Echo"\ n";Echo $a;//134Echo"\ n";Echo $c;//134Echo"\ n";$a= 342;Echo $c;//134Echo"\ n";Echo $b;//342Echo"\ n";@$b=& Test2 ($b);Echo $b;//442Echo"\ n";$c=&$b;$a= 154;Echo $c;//154Echo"\ n"; Test3 ($c);Echo $c;//0 $c and $and binding point to the same content, the method also binds the $and and $_get[' a '], but there is no variable $c within the Test3 method, the operation within the function is not in the $c scope of influenceEcho"\ n";$a= 111;functionTest (&$and){    return $and=$and+ 100;}functionTest2 ($and){    return $and=$and+ 100;}functionTest3 (&$and){    return $and&=$_get[' A '];//$_get[' a '] = 1}test (1);//1 is a constant is not a variable

= & Points Two variables to a value at the same time, and any one of the variable values changes and the other changes.

The parameter in the test method for example two is & $and returns the passed parameter $and, although the test ($b) is assigned to the $c, but $c is not an incoming parameter to test (), so $c does not change when the $b changes. The meaning of test (& $and) is that the value of passing in the parameter $and

php = &