PHP $GLOBALS Hyper-Global variable Analysis _php tutorial

PHP has a super global variable $globals that is not used by many people. Reasonable use of this variable can make the work more efficient, this article mainly analyzes the use of this super-global variable and the difference between $globals and global.

$GLOBALS definition: References all the variables available in the global scope (a globally combined array containing all the variables). The name of the variable is the key to the array, and unlike all other hyper-global variables, $GLOBALS is always available anywhere in the PHP code, and you can tell by printing the result of the $globals variable.

In the PHP life cycle, the so-called global variables that are defined outside the function body are not directly available inside the function. If you want to access externally defined global variables within the function body, you can use the global declaration or directly using $globals to access them, for example:

 
  '; global $var 1;echo $var 1, '
';    echo $GLOBALS [' var2 '];}

The result will be printed as:

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Here are the main explanations for the difference between global and $globals:

$GLOBALS [' var '] is the external global variable itself, and the global $var is an external $var reference or pointer, which means that global has a function that produces an alias variable that points to the external variable of the function, rather than the actual external variable of the function, and $globals[] It is true that the external variables are called, and the functions are always consistent inside and outside the function. Here's an example of how this is done:

$var 1=1; $var 2=2;function Test () {$GLOBALS [' var2 ']=& $GLOBALS [' var1 '];}  Test (); Echo $var 2;

Print result is 1

$var 1=1; $var 2=2;function Test () {global $var 1, $var 2; $var 2=& $var 1;}  Test (); Echo $var 2;

The print result is 2. Why would I print a result of 2? This is because $VAR1 's reference points to the $VAR2 's reference address. Causes the value of the substance to not change. Let's look at one more example.

$var 1=1;function Test () {unset ($GLOBALS [' var1 ']);}  Test (); Echo $var 1;

Because $var1 was removed, nothing was printed.

$var 1=1;function Test () {Global $var 1;unset ($var 1);}  Test (); Echo $var 1;

The print result is 1. To prove that the deletion is only an alias | reference, the value of itself has not been changed. This means that global $var is actually $var=& $GLOBALS [' var ']. Call an alias of an external variable.

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