Explain extract() in php.

 Q. Explain extract() in php.
Answer:
The extract() function in PHP is used to import variables from an associative array into the symbol table (i.e., the list of variable names in the current scope). This means that it can create variables with names and values based on the keys and values of the associative array. It's important to use extract() with caution because it can lead to unexpected variable collisions or overwrite existing variables.

Here's the basic syntax of extract():

bool extract(array &$array, int $flags = EXTR_OVERWRITE, string $prefix = '')

$array: The associative array from which variables will be extracted.
$flags: Optional. Specifies how to handle existing variables. It can take values like EXTR_OVERWRITE, EXTR_SKIP, EXTR_PREFIX_SAME, and others.
$prefix: Optional. If specified, all variable names will be prefixed with this string.
Here's a simple example:

<?php
$data = array(
    'name' => 'John Doe',
    'age' => 30,
    'city' => 'Example City'
);

// Extract variables from the array
extract($data);

// Now you can use $name, $age, and $city as variables
echo $name;  // Outputs: John Doe
echo $age;   // Outputs: 30
echo $city;  // Outputs: Example City
?>

In this example, extract($data) creates variables named $name, $age, and $city based on the keys in the associative array $data. The values of these variables are set to the corresponding values from the array.

It's important to be cautious when using extract() to avoid unintentional variable overwrites. If the array contains keys that clash with existing variables in the scope where extract() is called, it may lead to unexpected behavior. To mitigate this risk, you can use the $flags parameter to control how existing variables are handled.

Here's an example with the EXTR_PREFIX_SAME flag:

<?php
$data = array(
    'name' => 'John Doe',
    'age' => 30,
    'city' => 'Example City'
);

$age = 25;  // Existing variable

// Extract variables from the array with a prefix for existing variables
extract($data, EXTR_PREFIX_SAME, 'new');

// Now you can use $name, $newage, and $city as variables
echo $name;   // Outputs: John Doe
echo $newage;  // Outputs: 30
echo $city;    // Outputs: Example City
?>

In this example, the EXTR_PREFIX_SAME flag is used, so existing variables are prefixed with "new" to avoid overwriting them.