PHP extract() Function

Example

Assign the values "Cat", "Dog" and "Horse" to the variables $a, $b and $c:

<?php
$a = "Original";
$my_array = array("a" => "Cat","b" => "Dog", "c" => "Horse");
extract($my_array);
echo "\$a = $a; \$b = $b; \$c = $c";
?>

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Definition and Usage

The extract() function imports variables into the local symbol table from an array.

This function uses array keys as variable names and values as variable values. For each element it will create a variable in the current symbol table.

This function returns the number of variables extracted on success.

Syntax

extract(array, extract_rules, prefix)

Parameter Values

Parameter	Description
array	Required. Specifies the array to use
extract_rules	Optional. The extract() function checks for invalid variable names and collisions with existing variable names. This parameter specifies how invalid and colliding names are treated. Possible values: EXTR_OVERWRITE - Default. On collision, the existing variable is overwritten EXTR_SKIP - On collision, the existing variable is not overwritten EXTR_PREFIX_SAME - On collision, the variable name will be given a prefix EXTR_PREFIX_ALL - All variable names will be given a prefix EXTR_PREFIX_INVALID - Only invalid or numeric variable names will be given a prefix EXTR_IF_EXISTS - Only overwrite existing variables in the current symbol table, otherwise do nothing EXTR_PREFIX_IF_EXISTS - Only add prefix to variables if the same variable exists in the current symbol table EXTR_REFS - Extracts variables as references. The imported variables are still referencing the values of the array parameter
prefix	Optional. If EXTR_PREFIX_SAME, EXTR_PREFIX_ALL, EXTR_PREFIX_INVALID or EXTR_PREFIX_IF_EXISTS are used in the extract_rules parameter, a specified prefix is required. This parameter specifies the prefix. The prefix is automatically separated from the array key by an underscore character.

Parameter

Description

array

Required. Specifies the array to use

extract_rules

Optional. The extract() function checks for invalid variable names and collisions with existing variable names. This parameter specifies how invalid and colliding names are treated.

Possible values:

EXTR_OVERWRITE - Default. On collision, the existing variable is overwritten
EXTR_SKIP - On collision, the existing variable is not overwritten
EXTR_PREFIX_SAME - On collision, the variable name will be given a prefix
EXTR_PREFIX_ALL - All variable names will be given a prefix
EXTR_PREFIX_INVALID - Only invalid or numeric variable names will be given a prefix
EXTR_IF_EXISTS - Only overwrite existing variables in the current symbol table, otherwise do nothing
EXTR_PREFIX_IF_EXISTS - Only add prefix to variables if the same variable exists in the current symbol table
EXTR_REFS - Extracts variables as references. The imported variables are still referencing the values of the array parameter

prefix

Optional. If EXTR_PREFIX_SAME, EXTR_PREFIX_ALL, EXTR_PREFIX_INVALID or EXTR_PREFIX_IF_EXISTS are used in the extract_rules parameter, a specified prefix is required.

This parameter specifies the prefix. The prefix is automatically separated from the array key by an underscore character.

Technical Details

Return Value:	Returns the number of variables extracted on success
PHP Version:	4+
PHP Changelog:	The extract_rules value EXTR_REFS was added in PHP 4.3. The extract_rules values EXTR_IF_EXISTS and EXTR_PREFIX_IF_EXISTS were added in PHP 4.2. As of PHP 4.0.5, this function now returns the number of variables extracted. The extract_rules value EXTR_PREFIX_INVALID was added in PHP 4.0.5. As of PHP 4.0.5, the extract_rules value EXTR_PREFIX_ALL now includes numeric variables as well.

More Examples

Example

Using all parameters:

<?php
$a = "Original";
$my_array = array("a" => "Cat", "b" => "Dog", "c" => "Horse");

extract($my_array, EXTR_PREFIX_SAME, "dup");

echo "\$a = $a; \$b = $b; \$c = $c; \$dup_a = $dup_a";
?>

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❮ PHP Array Reference