PHP: Manual: extract

Description

void 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.

extract() checks for colissions with existing variables. The way 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 new variable with prefix.
EXTR_PREFIX_ALL: Prefix all variables with prefix.

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 or EXTR_PREFIX_ALL.

extract() checks each key to see if it constitues a valid variable name, and if it does only then does it proceed to import it.

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

Beispiel 1. extract example
<? /* 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, becaus 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.