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1- آیا اینکه آموزش های سایت w3schools خوب هستن برای یاد گیری php ? من به سفارش یکی از دوستان دارم از اونجا php رو یاد میگریم
سوال دومم مربوط به قسمتی از متغیر ها هست که در سایت w3schools توضیح داده و من هر چقدر میخونم نمیتونم بفهممش اگه دوستان در این راستا کمکم کنند ممنون آن ها میشم
این قسمت هست :
[h=2]PHP Variable Scope[/h]
[h=2]Local Scope[/h]
[h=2]Global Scope[/h]
[h=2]Static Scope[/h]
[h=2]Parameters[/h]
Parameters are also called arguments. We will discuss them in more detail when we talk about functions.
2 دو تا سوال داشتم
1- آیا اینکه آموزش های سایت w3schools خوب هستن برای یاد گیری php ? من به سفارش یکی از دوستان دارم از اونجا php رو یاد میگریم
سوال دومم مربوط به قسمتی از متغیر ها هست که در سایت w3schools توضیح داده و من هر چقدر میخونم نمیتونم بفهممش اگه دوستان در این راستا کمکم کنند ممنون آن ها میشم
این قسمت هست :
[h=2]PHP Variable Scope[/h]
The scope of a variable is the portion of the script in which the variable can be referenced.PHP has four different variable scopes:
[*=left]local
[*=left]global
[*=left]static
[*=left]parameter
[h=2]Local Scope[/h]
A variable declared within a PHP function is local and can only be accessed within that function. (the variable has local scope):
<?php
$a = 5; // global scope
function myTest()
{
echo $a; // local scope
}
myTest();
?>
$a = 5; // global scope
function myTest()
{
echo $a; // local scope
}
myTest();
?>
The script above will not produce any output because the echo statement refers to the local scope variable $a, which has not been assigned a value within this scope.You can have local variables with the same name in different functions, because local variables are only recognized by the function in which they are declared.Local variables are deleted as soon as the function is completed.
[h=2]Global Scope[/h]
Global scope refers to any variable that is defined outside of any function.Global variables can be accessed from any part of the script that is not inside a function.To access a global variable from within a function, use the global keyword:
<?php
$a = 5;
$b = 10;
function myTest()
{
global $a, $b;
$b = $a + $b;
}
myTest();
echo $b;
?>
$a = 5;
$b = 10;
function myTest()
{
global $a, $b;
$b = $a + $b;
}
myTest();
echo $b;
?>
The script above will output 15.PHP also stores all global variables in an array called $GLOBALS[index]. Its index is the name of the variable. This array is also accessible from within functions and can be used to update global variables directly.The example above can be rewritten as this:
<?php
$a = 5;
$b = 10;
function myTest()
{
$GLOBALS['b'] = $GLOBALS['a'] + $GLOBALS['b'];
}
myTest();
echo $b;
?>
$a = 5;
$b = 10;
function myTest()
{
$GLOBALS['b'] = $GLOBALS['a'] + $GLOBALS['b'];
}
myTest();
echo $b;
?>
[h=2]Static Scope[/h]
When a function is completed, all of its variables are normally deleted. However, sometimes you want a local variable to not be deleted.To do this, use the static keyword when you first declare the variable:
static $rememberMe;
Then, each time the function is called, that variable will still have the information it contained from the last time the function was called.Note: The variable is still local to the function.
[h=2]Parameters[/h]
A parameter is a local variable whose value is passed to the function by the calling code.Parameters are declared in a parameter list as part of the function declaration:
function myTest($para1,$para2,...)
{
// function code
}
{
// function code
}
Parameters are also called arguments. We will discuss them in more detail when we talk about functions.
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