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# extract

(3.0.7 - 3.0.18 only, PHP 4 >= 4.0.0)

extract -- Import variables into the symbol table from an array

## Description

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

This function is used to import variables from an array into the current symbol table. It takes associative array `var_array` and treats keys as variable names and values as variable values. For each key/value pair it will create a variable in the current symbol table, subject to `extract_type` and `prefix` parameters.

> Note: Since version 4.0.5 this function returns the number of variables extracted.

extract() checks each key to see whether if constitutes a valid variable name and also for collisions with existing variables in the symbol table. The way invalid/numeric keys and collisions are treated is determined by `extract_type`. It can be one of the following values:

EXTR_OVERWRITE

  If there is a collision, overwrite the existing variable.

EXTR_SKIP

  If there is a collision, don't overwrite the existing variable.

EXTR_PREFIX_SAME

  If there is a collision, prefix the variable name with `prefix`.

EXTR_PREFIX_ALL

  Prefix all variable names with `prefix`. Since PHP 4.0.5 this includes numeric ones as well.

EXTR_PREFIX_INVALID

  Only prefix invalid/numeric variable names with `prefix`. This flag has been added in PHP 4.0.5.

If `extract_type` is not specified, it is assumed to be EXTR_OVERWRITE.

Note that `prefix` is only required if `extract_type` is EXTR_PREFIX_SAME, EXTR_PREFIX_ALL, or EXTR_PREFIX_INVALID. If the prefixed result is not a valid variable name, it is not imported into the symbol table.

extract() returns the number of variables successfully imported into the symbol table.

A possible use for extract is to import into symbol table variables contained in an associative array returned by wddx_deserialize().

Example 1. extract() example
    <?php

    /* Suppose that $var_array is an array returned from
       wddx_deserialize */

    $size = "large";
    $var_array = array ("color" => "blue",
                        "size"  => "medium",
                        "shape" => "sphere");
    extract ($var_array, EXTR_PREFIX_SAME, "wddx");

    print "$color, $size, $shape, $wddx_size\n";

    ?>

The above example will produce:

    blue, large, sphere, medium

The `$size` wasn't overwritten, because we specified EXTR_PREFIX_SAME, which resulted in `$wddx_size` being created. If EXTR_SKIP was specified, then $wddx_size wouldn't even have been created. EXTR_OVERWRITE would have cause `$size` to have value "medium", and EXTR_PREFIX_ALL would result in new variables being named `$wddx_color`, `$wddx_size`, and `$wddx_shape`.

You must use an associative array, a numerically indexed array will not produce results.

See also: compact().

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