# Creating Recursion Functions for Counting

Tue Feb 02, 2010 11:00 am
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 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 built-in 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.