PHP extract () function converts variables in data to PHP variables _php tutorial

The PHP extract () function imports variables from the array into the current symbol table. For each element in the array, the key name is used for the variable name, and the key value is used for the variable value. The second parameter type is used to specify how the extract () function treats conflicts when a variable already exists and the element with the same name in the array.

Register the variable from the PHP array as a global variable, implement the key name as the variable name, and the value as the value of the variable, as follows

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$vars = Array (' var1 ' = ' 1 ', ' var2 ' = ' 2 ', ' var3 ' = ' 3 ', ' var4 ' = ' 4 ', ' var5 ' = ' 5 ');

The implementation is accessed by means of a key name as a variable name, such as: $var 1, $var 2

The first scenario: Use the PHP built-in extract () function, as follows

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Extract ($vars);

Second scenario: Register as a global variable with a foreach loop array, as follows

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foreach ($vars as $k = = $v) { $GLOBALS [$k] = $v; }

The second scenario is recommended because of the performance and security issues with the extract () function.

Extract () function description

(PHP 3 >= 3.0.7, PHP 4, PHP 5)
Extract--Import variables from an array into the current symbol table

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int extract (array var_array [, int extract_type [, string prefix]])

This function is used to import variables from the array into the current symbol table. Accept the associative array var_array as the argument and use the key name as the variable name, and the value as the value of the variable. For each key/value pair, the variables are created in the current symbol table and are affected by the Extract_type and prefix parameters.

Reference table

Parameters	Description
Array	Necessary. Specifies the input to use.
extract_rules	Optional. The extract () function checks to see if each key name is a valid variable name, and also checks whether the variable names in the symbol table conflict. The handling of illegal, numeric, and conflicting key names is determined by this parameter. Can be one of the following values: Possible values: extr_overwrite-default. If there is a conflict, overwrite the existing variable. Extr_skip-If there is a conflict, do not overwrite the existing variable. (ignores elements with the same name in the array) extr_prefix_same-If there is a conflict, precede the variable name with the prefix PREFIX. Since PHP 4.0.5, this also includes the processing of the digital index. extr_prefix_all-Prefix all variable names with PREFIX (the third argument). extr_prefix_invalid-prefix PREFIX is only preceded by an illegal or numeric variable name. This tag is a new addition to PHP 4.0.5. extr_if_exists-Overrides the value of a variable with the same name in the current symbol table only if it already exists. None of the others will deal with it. It can be used where a set of valid variables has been defined and then extracted from an array such as $_request to override those variables. This tag is a new addition to PHP 4.2.0. extr_prefix_if_exists-A variable name with the prefix appended to it is created only if a variable with the same name already exists in the current symbol table, and none of the others are processed. This tag is a new addition to PHP 4.2.0. extr_refs-Extracts the variable as a reference. This strongly demonstrates that the imported variable still references the value of the Var_array parameter. This flag can be used alone or in conjunction with any other flag in Extract_type. This tag is a new addition to PHP 4.3.0.
Prefix	Optional. Note that prefix is required only if the value of Extract_type is Extr_prefix_same,extr_prefix_all,extr_prefix_invalid or extr_prefix_if_exists. If the result appended with the prefix is not a valid variable name, it will not be imported into the symbol table. An underscore is automatically added between the prefix and the array key name.

Use all parameters:

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!--? php $a = & #39; original& #39; $my _array = Array ("A" => "Cat", "B" => "Dog", "C" => "Horse"); Extract ($my _array, Extr_prefix_same, & #39;d up& #39;); Echo $a = $a; $b = $b; $c = $c; $dup _a = $dup _a; "; ?> Output: $a = Original; $b = Dog; $c = Horse; $dup _a = Cat; http://www.bkjia.com/phpjc/445314.html Span id= "Indexurl" itemprop= "Indexurl" >www.bkjia.com true http://www.bkjia.com/phpjc/445314.html techarticle php Extract () The function imports variables from the array into the current symbol table. For each element in the array, the key name is used for the variable name, and the key value is used for the variable value. The second parameter, type, is used to refer to ... & #xe63a;-->