PHP Global variables and classes with full parse _php tutorial

Scenario 1:

Father.php is defined as follows:

$jack = 1000;

?>

Children.php is defined as follows:

Require ("father.php");

$jack = 123;

echo $jack. " /n ";

?>

PHP children.php

The run output is 123.

If $jack=123 is commented out, it runs at 1000, and if $jack=123 is dropped to require ("father.php"), the run result is 1000.

Good understanding: PHP Interpretation of the implementation, explain to where, where to execute. Like $jack, this is a global variable, such as the first case of the initial use of it is 1000, is in the Require

, the result is changed to 123, so the output of the running result is 123.

Scenario 2:

Change the children.php code to read as follows:

Require ("father.php");

function Testjack () {

if (!isset ($jack)) {

Echo ' $jack is null '. " /n ";

}

}//testjack

Testjack ();

?>

PHP children.php

The results are: $jack is null. This means that the $jack referenced in Testjack () is a local variable.

If you use the Global keyword, declare that the $jack is a global variable and the code changes to the following:

Require ("father.php");

function Testjack () {

Global $jack;

if (!isset ($jack)) {

Echo ' $jack is null '. " /n ";

}else{

Echo ' $jack is not null '. " /n ";

}

}//testjack

Testjack ();

?>

The result of the operation is $jack are not null!

Scenario 3:

The children.php code is as follows:

Require ("father.php");

Class jacktest{

Public Function Testjack () {

if (!isset ($jack)) {

Echo ' $jack is null '. " /n ";

}else{

Echo ' $jack is not null '. " /n ";

}

}//testjack

}

$jackTest = new Jacktest ();

$jackTest->testjack ();

?>

Run result output: $jack is null

This is because the $jack of this function in class is a local variable.

If you add global $jack at the start of function testjack, then the output $jack is not null.

Relatively easy to understand.

Scenario 4:

Load the file name as a parameter dynamically, the code is as follows:

$casefile = $_server[' argv '][1];

echo $casefile. " /n ";

Require ($casefile);

echo $jack. " /n ";

?>

Run PHP children.php father.php

The results are as follows:

father.php

1000

This means that our dynamic loader is running successfully.

Scenario 5:

To combine dynamic loading with the definition of a class:

Directory-Relational:
|-c.php
|-bfold-b.php
|-afold-a.class.php (the function inside refers to the: /bfold/b.php)

That is to say, in c.php new class A.class, and a.class.php a function require Bfold folder b.php, this require (.. /bfold/b.php) error, Warning: ...

Because you let the server is currently executing the c.php file, so PHP parsing is the path relative to the c.php, you try to put (.. /bfold/b.php) Change to (bfold/b.php) look, should not error.

The following is an example of a program that uses require_once (a.php) inside a function.

Understanding of the Require_once:

Suppose require_once (a.php) is referenced in b.php; This statement:

Then it is the equivalent of calling a.php, the anonymous lambda function to execute. Such as:

C.php in a function call require the b.php------"

b.php require the a.php--------in the ordinary statement

a.php

Now we call PHP b.php, because b.php uses require in the normal statement to call a.php, then a.php will be a variable of its relative a global variable, registered in the b.php environment. Because b.php is the root to start calling the file, his environment is the global environment. Therefore, the variables in the a.php file can be used normally in b.php.

Now we call PHP c.php, then C is the function using require call b.php, and then B called a, feel in the process of this call, relative B and A root run environment is C call function environment, but C call function if you want to use B and The variable in a, there is no way out.

If you use global $a to reference, then because $a in this case does not belong to the global variable, the reference is not.

If you use $a to refer to, then because $a will be used as a local variable also can not be referenced ...

http://www.bkjia.com/PHPjc/477354.html www.bkjia.com true http://www.bkjia.com/PHPjc/477354.html techarticle The situation is defined as follows: PHP $jack = 1:father.php;? children.php as defined below: PHP require (father.php); $jack =123; Echo $jack./n; php The children.php run output is 123. If ...

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