Introduction to various usages of extract functions in PHP

Directly on the code:

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<?php $my _array = Array ("A" => "Cat", "B" => "Dog", "C" => "horse"); Extract ($my _array); echo "$a = $a; $b = $b; $c = $c "; ?>

Guess what will come out?

Output:

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$a = Cat; $b = Dog; $c = Horse

No variable $a $b $c, no assignment, why can I get the value?

For example, can easily extract $_post or $_get elements, the form submitted to the content can not use one by one assignment, directly using the following code:

Form.html

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<form action= "action.php" method= "POST" > <input type= "text" name= "username" > <input type= "password" name= "password" > <input type= "Submit" >

Use the Extract () function in action.php to unlock the $_post global data:
action.php

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<?php Extract ($_post); Equivalent to $username = $_post[' username ']; $password = $_post[' password ']; ?>

Array operations

Related examples:

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<?php /* Assume that the $var _array is an array returned by Wddx_deserialize * * $size = "large"; $var _array = Array ("Color" => "Blue", "Size" => "medium", "Shape" => "sphere"); Extract ($var _array, Extr_prefix_same, "WDDX"); echo "$color, $size, $shape, $wddx _sizen"; ?>

The example above will output:

Blue, large, sphere, medium.
The $size is not covered because the extr_prefix_same is specified, which makes the $WDDX _size built. If Extr_skip is specified, the $WDDX _size will not be established. Extr_overwrite will make the value of $size "medium", Extr_prefix_all will create a new variable $wddx _color, $wddx _size and $wddx _shape.

Array 2

. Scope of application: Non-numeric index array, the array has the key value pairs;
2. The variable name created by the function is the keyword in the array, and the value of the variable is the corresponding value in the array;
3. Two optional parameters: Extract_type and prefix;
Where Extract_type specifies the method of handling variable name conflicts by default Extr_overwrite, which means overwriting existing variables.
When the value of the Extract_type is Extr_prefix_all, prefix all the created variables with a prefix of PREFIX parameters;
4. The keyword for the element in the array must be a valid variable name or it will be skipped.

Instance:

array_extract.php:

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<title>test Array extract</title> <body> <?php $array = Array (' Key1 ' => ' value1 ', ' key2 ' => ' value2 ', ' Key3 ' => ' value3 '); Extract ($array); echo ' default:<br/> '; echo "$key 1 $key 2 $key 3<br/>"; Skip an element when a conflict occurs $key 1 = "abc"; Extract ($array, extr_skip); echo ' skip:<br/> '; echo "$key 1 $key 2 $key 3<br/>"; Precede all variable names with the values provided by the prefix parameter Extract ($array, Extr_prefix_all, ' my '); echo ' prefix_all:<br/> '; echo "$my _key1 $my _key2 $my _key3<br/>"; ?> </body>

is

Convenient?
about this function with an introduction to refer to http://www.111cn.net/phper/24/04ef3db43c8278b93cdd9203999b8352.htm