PHP Exercises: Call a given function only once
PHP: Exercise-101 with Solution
Write a PHP program to call a given function only once.
Sample Solution:
PHP Code:
<?php
// Licence: https://bit.ly/2CFA5XY
// Function definition for 'once' that takes a function as a parameter
function once($function)
{
// Return a closure that encapsulates the original function
return function (...$args) use ($function) {
// Static variable to track whether the function has been called
static $called = false;
// If the function has been called before, return early without executing the original function
if ($called) {
return;
}
// Mark the function as called and execute the original function with the provided arguments
$called = true;
return $function(...$args);
};
}
// Anonymous function definition for 'add' that takes two parameters and returns their sum
$add = function ($a, $b) {
return $a + $b;
};
// Create a 'once' version of the 'add' function
$once = once($add);
// Call the 'once' version of 'add' with arguments and display the result using 'var_dump'
var_dump($once(10, 5)); // Output: int(15)
// Attempt to call the 'once' version of 'add' again with different arguments
// The second call should return early without executing the original function
var_dump($once(20, 10)); // Output: NULL
?>
Sample Output:
int(15) NULL
Flowchart:
PHP Code Editor:
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