_php tutorial on value passing and reference passing in PHP

Value passing and reference passing are present in PHP. The latter needs to use the address character & to identify the variable. Examples of using assignment operations are as follows:

1. Value passing

1) Basic Data type:

01
02
$a = 1;
03
$b = $a;
04
$b + = 2;
05

06
echo "\ $a =". $a. "
";
07
echo "\ $b =". $b. "
";
08

09
/* Output:
10
$a = 1
11
$b = 3
12
*/
13
?>
Note: The $b = $a statement is used here to assign a value of $ A to $b. That is, the value assigned at this time is 1.

Execute statement $b + = 2:

So, $b becomes 3, but the value of $ A does not change.

2) Reference data type

The person class is as follows:

01
Class Person {
02
Private $_name;
03

04
Public Function SetName ($name) {
05
$this->_name = $name;
06
}
07

08
Public Function GetName () {
09
return $this->_name;
10
}
11

12
Public Function toString () {
13
Return "name is". $this->_name;
14
}
15
}
Initialize the two Person class object and set the properties:

1
$p 1 = new person ();
2
$p 1->setname ("Person1");
3
$p 2 = new Person ();
4
$p 2->setname ("Person2");
Perform the following actions:

1
$p 3 = $p 1;
Test:

1
echo "\ $p 1 ' s". $p 1->tostring (). ".
";
2
echo "\ $p 3 ' s". $p 3->tostring (). ".
";
3

4
/* Output:
5
$p 1 ' s name is Person1.
6
$p 3 ' s name is Person1.
7
*/
Note: for $p 3 = $p 1 statement, the value assigned at this time is 0x000a. That is, both $P1 and $P3 refer to the same object.

2. Reference delivery

1) Basic Data type

01
02
$a = 1;
03
$b = & $a;
04
$b + = 2;
05

06
echo "\ $a =". $a. "
";
07
echo "\ $b =". $b. "
";
08

09
/* Output:
10
$a = 3
11
$b = 3
12
*/
13
?>
Note: The $b = & $a statement is used here to pass the reference: that is, the value assigned at this time is 0x0001.


So on $b + = 2,

So the value of $ A and $b is 3.

2) Reference data type

If you are performing the following actions to replace the previous $P3 = $p 1

1
$p 3 = & $p 1;
Then do the following:

1
$p 3 = $p 2;
The test results are as follows:

1
echo "\ $p 1 ' s". $p 1->tostring (). ".
";
2
echo "\ $p 3 ' s". $p 3->tostring (). ".
";
3

4
/* Output:
5
$p 1 ' s name is Person2.
6
$p 3 ' s name is Person2.
7
*/
Note: It is clear that the result information that has been printed out is $P3 because the $P3 = $p 2 statement is executed, but why is the result information printed $P1 different than before?

is because $P3 = & $p 1 statement is executed, that is, the value assigned at this time is 0x0001.

Immediately after executing $P3 = $p 2 statement

That's why the result information is printed as above, and this is where the address character & is working.

The complete code is as follows:

1) Reference data type

php
!--?/-->02
class Person {
$_name
Private;



Public Function SetName ($name) {

$this->_name = $name;
"
}
"

"
Public Function GetName () {
Ten
return $this->_name;

}


All
Public Function toString () {
+
Return ' name is '. $this->_name;

}

}
1


$p = new Person ();

$p 1->setname ("Person1");

$p 2 = new Person ();

$p 2->setname ("Person2");


3
$p = $p 1;

//$p 3 = & $p 1;

//$p 3 = $p 2;

echo \ $p 1 ' s ". $p 1->tostring ().".
";

echo \ $p 3 ' s. $p 3->tostring (). ".
";

;
2) basic data type

1
2
$a = 1;
3
$b = $a;
4
$b = & $a;
5
$b + = 2;
6

7
echo "\ $a =". $a. "
";
8
echo "\ $b =". $b. "
";
9
?>
Concluding remarks: For value passing and reference passing on method/function arguments, the condition is similar to the assignment operation.

http://www.bkjia.com/PHPjc/478049.html www.bkjia.com true http://www.bkjia.com/PHPjc/478049.html techarticle value passing and reference passing are present in PHP. The latter needs to use the address character to identify the variable. An example of using an assignment operation is as follows: 1, Value pass 1) Basic data type: £ º PHP $a ...

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