In this article, you will learn how to fill the local symbol table with the variables using the keys and values of an array.
The PHP extract() function takes the keys and values from the given array and fills the local symbol table. The keys are used as the name of the variables and the values are used as the value of the variable.
Tip: You can consider the extract function as the opposite of the compact() function.
What is the syntax of the extract() function in PHP?
extract(array, extract_rules, prefix)
| Parameter | Description |
|---|---|
| array | The array to extract variable name and value from – Required |
| extract_rules | (optional parameter) This parameter checks for the validity of the variable names being extracted from the array. Also, it checks if a variable name is already created by using the following possible flags. EXTR_OVERWRITE – Existing variable is overwritten on repetition EXTR_SKIP – The existing variable is not overwritten on repetition EXTR_PREFIX_SAME – The variable name will be given a prefix on repetition EXTR_PREFIX_ALL – All variable names are assigned prefix EXTR_PREFIX_INVALID – Only invalid or numeric variable names are assigned a prefix EXTR_IF_EXISTS – If existing variables are found, overwrite them EXTR_PREFIX_IF_EXISTS – If existing variables are found, add the prefix to them EXTR_REFS – Extracts variable as reference. These are still pointing to the values of the array parameter |
| prefix | Specify prefix which is automatically separated from the array key using an underscore (optional) Can be used only if If EXTR_PREFIX_SAME, EXTR_PREFIX_ALL, EXTR_PREFIX_INVALID or EXTR_PREFIX_IF_EXISTS rules are applied in extract_rules parameter |
Examples of the extract() function
Example 1. Create some variables with values using an array.
<?php
$a = "dumy-value";
$arr= array("a" => "1","b" => "2", "c" => "3");
extract($arr);
echo "\$a = $a; \$b = $b; \$c = $c";
?>Example 2. The following example shows the use of the extract() method with all parameters.
<?php
$a = "dumy-value";
$arr= array("a" => "1","b" => "2", "c" => "3");
extract($my_array, EXTR_PREFIX_SAME, "dup");
echo "\$a = $a; \$b = $b; \$c = $c; \$dup_a = $dup_a";
?>
