Import variables into the current symbol table from an array

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- PHP Manual
- Array Functions
- Import variables into the current symbol table from an array

# extract

(PHP 4, PHP 5, PHP 7, PHP 8)

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

### Description

extract(array `&$array`, int `$flags` = `EXTR_OVERWRITE`, string `$prefix` = ""): int

Import variables from an array into the current symbol table.

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

Warning

Do not use extract() on untrusted data, like user input (e.g. $_GET, $_FILES).

### Parameters

`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 `flags` 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`.

`flags`

  The way invalid/numeric keys and collisions are treated is determined by the extraction `flags`. 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 `array` parameter. You can use this flag on its own or combine it with any other flag by OR'ing the `flags`.

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

`prefix`

  Note that `prefix` is only required if `flags` 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.

### 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 (i.e. $_GET, $_FILES, etc.). If you do, make sure you use one of the non-overwriting `flags` 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() - Create array containing variables and their values
- list() - Assign variables as if they were an array