This function is used to import variables from an array into the current symbol table. It takes an 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.
Beginning with version 4.0.5, this function returns the number of variables extracted.
EXTR_PREFIX_IF_EXISTS were introduced in version 4.2.0.
EXTR_REFS was introduced in version 4.3.0.
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. The way invalid/numeric keys and collisions are treated is determined by the extract_type. It can be one of the following values:
If extract_type is not specified, it is
assumed to be
Note that prefix is only required 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.
extract() returns the number of variables successfully imported into the symbol table.
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
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
/* Suppose that $var_array is an array returned from
$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
$size wasn't overwritten, because we
EXTR_PREFIX_SAME, which resulted in
$wddx_size being created. If
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
You must use an associative array, a numerically indexed array
will not produce results unless you use
See also compact().