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PHP extract() Function

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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 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.

Example 1

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

The output of the code above will be:

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

Example 2

With all parameters in use:

<?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;";
?>

The output of the code above will be:

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

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