PHP Array Element Extract Function, extract(), Syntax Example

Topic

What is extract() Function?

Explanation

The "extract()" function import variables into the current symbol table from an array. This function uses array keys as variable names, values as variable values. For each element it will create a variable in the current symbol table

Syntax:

    extract(array,extract_rules,prefix)

In the above syntax "array" is the array from which the variables are imported to the current symbol table.

The following is the description of the Extract_rules parameters.

Parameter	Description
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 invalid or numeric variable names will be given a prefix./td>
EXTR_IF_EXISTS	Only overwrite existing variables in the current symbol table, otherwise do nothing
EXTR_PREFIX_IF_EXISTS	Only add prefix to variables if the same variable exists in the current symbol table.
EXTR_REFS	Extracts variables as references. The imported variables are still referencing the values of the array parameter.

The "prefix" parameter is seperated by an underscore, both "extract rules", "prefix" are optional parameters.

Example:

    <?php
    $size = "large";
    $var_array = array("color" => "blue",
                   "size"  => "medium",
                   "shape" => "sphere");
    extract($var_array, EXTR_PREFIX_SAME, "dup");

    echo "$color, $size, $shape, $dup_size\n";
    ?>

Result:

    blue, large, sphere, medium

In the above example there is a collision for the variable "$size" so using the extracting rule "EXTR_PREFIX_SAME", the variable $size value that is "large" is added for size and using the prefix "dup" with size, the value "medium" is displayed.

PHP Array extract() Function