There are many reasons to use recursion functions. Here we are going to use such a technique to count, instead of using the traditional looping methods (for, do, do while, while). Recursion functions are functions that at some point recall themselves. This is in effect a loop. The possible uses of such a function are creating categorizational structures, mathematics or just simple loops. 1. Create a recursion function to count from 1 to 10. function recursive($start,$end) { echo "$start "; if($start < $end){$x = recursive($start+1,$end);} } echo recursive(1,10); produces: 1 2 3 4 5 6 7 8 9 10 In the above function we require two variables, the number to start from and the number to end on. This is a simple linear function. If you wanted to utilize other functions in mathematics you could just adjust the function. 2. Create a recursive function to count from 1 to 5 and take each number up to the third power. function recursive($start,$end) { $a = pow($start,3); echo "$a "; if($start < $end){$x = recursive($start+1,$end);} } echo recursive(1,5); produces: 1 8 27 64 125 pow() is a builtin PHP function and requires two variables. The first number is the number you want to start with and the second is by what power to increase it.
