How can I make this function work with recursion? - php

Question

Output:
3
3 4
3 4 5
3 4 5 6
3 4 5 6 7
3 4 5 6 7 8
function Triangle ($begin, $end) {
if ($begin < 0 || $end < 0) {
return;
}
if ($begin == $end) {
return $a;
}
else {
// non recursive
for ($i = 1; $i <= $end; $i++) {
for ($j = $begin; $j <= $i; $j++) {
echo $j . " ";
}
echo "<br>";
}
}
}
This is what I made so far.

Answer 1

Here's one way:
function triangle ($begin, $end, $row = 1) {
//stop when we've printed up to end
if($end - $begin + 1 < $row) return;
//let's start at the beginning :)
for($i = 0; $i < $row; $i++){
//the row number increments each time so we can keep adding.
echo ($begin + $i)." ";
}
echo "<br>";
//now recurse...
triangle($begin, $end, $row + 1);
}
Usage:
triangle(3,9);
Output:
3
3 4
3 4 5
3 4 5 6
3 4 5 6 7
3 4 5 6 7 8
3 4 5 6 7 8 9

Answer 2

This should work for you:
(Here I just added the variable step which defines how many steps you make from $begin to $end and if $begin + $step == $end the function is done. If not It starts from $begin and makes X steps and as long as it doesn't reach the end I call the function again with a step more)
<?php
function Triangle($begin, $end, $step = 0) {
for($count = $begin; $count <= ($begin+$step); $count++)
echo "$count ";
echo "<br />";
if(($begin + $step) == $end)
return;
else
Triangle($begin, $end, ++$step);
}
Triangle(3, 8);
?>
output:
3
3 4
3 4 5
3 4 5 6
3 4 5 6 7
3 4 5 6 7 8