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PHP extract() Function

< PHP Array Reference

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";
?>
Run example »

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 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+
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 1

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";
?>
Run example »
< PHP Array Reference