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 for colissions with existing variables. The way 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 new variable with prefix.
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().