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Recursive Functions are functions that auto-call themself. Generally, a recursive function returns a value that are passed as argument, so the value is passed from an auto-call to the other, until it is returned.
Recursive functions are very useful in equations with factorial numbers and some operatios with multi-dimensional array.
Factorials are written like 6! and this means: 6 * 5 * 4 * 3 * 2 * 1. So 6! is 4320 and 4! is 24.
In the fallowing example we have a recursive function that finds the factorial of a number "$nr" (here 8).

<?php
// this function auto-calls itself (decrementing $nr) until $nr is 0
function factorial($nr) {
 if($nr > 0) $re = $nr * factorial($nr-1);
 else if($nr == 0) $re = 1;

 return $re;
}

echo '8 factorial is: '. factorial(8); // 8 factorial is: 45360
?>

- To see another example, visit this page: Get all the unique numbers from two-dimensional array.

Daily Test with Code Example

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What attribute makes an option from <select> selected?
checked="checked" selected="selected" disabled="disabled"
<select name="a_name">
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contain repeat-x linear-gradient
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}
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[] {} new Object()
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alert(arr[2]);
Indicate the PHP function used to redirect to other page.
function() header() switch()
header("Location: http://coursesweb.net/");
exit;
Recursive Functions in PHP

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