end
in_array
Array Functions
PHP Manual

# extract

(PHP 4, PHP 5)

extract — Import variables into the current symbol table from an array

### Description

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

Import variables from an array into the current symbol table.

extract() checks each key to see whether it has a valid variable name. It also checks for collisions with existing variables in the symbol table.

### Parameters

`var_array`

  An associative array. This function 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.

  You must use an associative array, a numerically indexed array will not produce results unless you use `EXTR_PREFIX_ALL` or `EXTR_PREFIX_INVALID`.

`extract_type`

  The way invalid/numeric keys and collisions are treated is determined by the `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` .
  `EXTR_PREFIX_INVALID`
    Only prefix invalid/numeric variable names with `prefix` .
  `EXTR_IF_EXISTS`
    Only overwrite the variable if it already exists in the current symbol table, otherwise do nothing. This is useful for defining a list of valid variables and then extracting only those variables you have defined out of $_REQUEST, for example.
  `EXTR_PREFIX_IF_EXISTS`
    Only create prefixed variable names if the non-prefixed version of the same variable exists in the current symbol table.
  `EXTR_REFS`
    Extracts variables as references. This effectively means that the values of the imported variables are still referencing the values of the `var_array` parameter. You can use this flag on its own or combine it with any other flag by OR'ing the `extract_type` .

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

`prefix`

  Note that `prefix` is only required if `extract_type` is `EXTR_PREFIX_SAME`, `EXTR_PREFIX_ALL`, `EXTR_PREFIX_INVALID` or `EXTR_PREFIX_IF_EXISTS`. If the prefixed result is not a valid variable name, it is not imported into the symbol table. Prefixes are automatically separated from the array key by an underscore character.

### Return Values

Returns the number of variables successfully imported into the symbol table.

### ChangeLog

Version | Description
--- | ---
4.3.0 | `EXTR_REFS` was added.
4.2.0 | `EXTR_IF_EXISTS` and `EXTR_PREFIX_IF_EXISTS` were added.
4.0.5 | This function now returns the number of variables extracted. `EXTR_PREFIX_INVALID` was added. `EXTR_PREFIX_ALL` includes numeric variables as well.

### Examples

Example#1 extract() example

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

`<?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");
echo "$color, $size, $shape, $wddx_size\n";
?>`

The above example will output:

    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 caused $size to have value "medium", and `EXTR_PREFIX_ALL` would result in new variables being named $wddx_color, $wddx_size, and $wddx_shape.

### Notes

Warning

Do not use extract() on untrusted data, like user-input ($_GET, ...). If you do, for example, if you want to run old code that relies on register_globals temporarily, make sure you use one of the non-overwriting `extract_type` values such as `EXTR_SKIP` and be aware that you should extract in the same order that's defined in variables_order within the php.ini.

### See Also

- compact()

end
in_array
Array Functions
PHP Manual