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:
If there is a collision, overwrite the existing variable.
If there is a collision, don't overwrite the existing variable.
If there is a collision, prefix the variable name with prefix.
Prefix all variable names with prefix. Since PHP 4.0.5 this includes numeric ones as well.
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
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().