How to do nested loop in descending order? - php

Question

What I want to get with for loop. Something will be like this.
*
**
***
****
*****
****
***
**
*
This thing I want to create right now I have this code.
<?php
$i = 1;
$end = 5;
$star = "*";
for($i; $i <= $end; $i++){
for($b=1; $b <= $i; $b++){
echo $star;
}
if($i == $end){
for($c=1; $c <= $end; $c++ ){
for($d=i; $d >= 2; $d--){
echo $star;
}
echo "<br>";
}
}
};
?>
And it's working fine with
*
**
***
****
*****
But then I need opposite loop first 4 then 3 then 2 then 1...
Where am I going wrong with this?

Answer 1

Just for fun. Try this:
$stars = 1;
for ($i = 0; $i < 9; $i++) {
for ($s = 1; $s <= $stars; $s++) {
echo "*";
}
echo "\n";
$stars += ($i<4)?1:-1;
}
And, for even more fun, one with just one for loop:
$stars = 0;
$starctr = 0;
for ($i = 0; $i < 25; $i++) {
echo "*";
if ($stars == $starctr) {
echo "\n";
$stars += ($i<14)?1:-1;
$starctr = 0;
} else {
$starctr++;
}
}

Answer 2

Can using nested for loop. Example:
$n = 5;
for($i = 1; $i <= $n; $i++){
for($j = 1; $j <= $i; $j++){
echo '*';
}
echo '<br />';
}
for($i = $n-1; $i >= 1; $i--){
for($j = $i; $j >= 1; $j--){
echo '*';
}
echo '<br />';
}
Another technique using array_fill(), array_map(), array_reverse()
$n = 5; $arr = array();
for($i = 1; $i <= $n; $i++){
$arr[] = array_fill(0, $i, '*');
}
array_map(function($v){echo join('', $v) . '</br>';},$arr);
unset($arr[count($arr) - 1]); //remove last index value
array_map(function($v){echo join('', $v) . '</br>';},array_reverse($arr));

Answer 3

<?php
for($i=0;$i<=6;$i++){
for($k=6;$k>=$i;$k--){
echo " ";
}
for($j=1;$j<=$i;$j++){
echo "* ";
}
echo "<br>";
}
for($i=5;$i>=1;$i--){
for($k=6;$k>=$i;$k--){
echo " ";
}
for($j=1;$j<=$i;$j++){
echo "* ";
}
echo "<br>";
}
?>

Answer 4

This can be achieved with only 2 for loops.
$offset = 1;
for ($i = 1; $i > 0; $i += $offset)
{
for($j = 1; $j <= $i; $j++){
echo '*';
}
echo '<br />';
if ($i === 5)
$offset = -1;
}

Answer 5

<?php
$i = 1;
$end = 5;
$star = "*";
for($i; $i <= $end; $i++){
for($b=1; $b <= $i; $b++){
echo $star;
}
};
for($c=$send; $c>=2; $c-- ){
for($d=$end; $d >= 2; $d--){
echo $star;
}
echo "<br>";
};
?>

Answer 6

Using a single for loop:
$end = 5;
$out = array();
for ($i=0;$i<$end;++$i)
{
$out[] = str_repeat('*', $i+1);
}
echo implode(PHP_EOL, $out).PHP_EOL;
array_pop($out);
$out = array_reverse($out);//remove last ****** <-- only one line with 5 stars
echo implode(PHP_EOL, $out).PHP_EOL;
Replace PHP_EOL with <br> if you want to, but this is the least loopy way to write this code I can think of
live demo

Answer 7

Here's a recursive attempt:
function ladder($n, $counter=1, &$acc=array())
{
if ($counter == ($n*2)) {
return implode($acc);
}
if ($counter <= $n) {
$acc[$counter] = str_repeat('*', $counter) . "\n";
$counter++;
}
if ($counter > $n) {
$diff = (int) $n-$counter;
$acc[$counter] = str_repeat('*', $n+$diff) . "\n";
$counter++;
}
return ladder($n, $counter, $acc);
}
print_r(ladder(5));