# Program that prints star pattern

I have a program that prints the star pattern.

Starr Pattern is:

          *
*
*
*
* * * * * * * * *
*
*
*
*


My code is:

$n=5; for($i=0; $i<$n; $i++){ for($k=$n-$i; $k>0;$k--){
echo ' '.' ';
}
for($j=0;$j< ($tot =$i+1); $j++){ if($i==$j &&$tot<$n){ echo '* '; }else{ if($tot<$n){ echo ' '.' '; }else{ echo '* '; } } } if($i == ($n-1)){ for($l=$n-1;$l>0;$l--){ echo '* '; } } echo '<br/>'; } for($i=0;$i<$n;$i++){ for($k=$n-$i; $k>0;$k--){
echo ' '.' ';
}

for($j=0;$j< ($tot =$i+1); $j++){ if($i==$j &&$tot<$n){ echo '* '; }else{ echo ' '.' '; } } echo '<br/>'; }  My question is that how can I calculate the complexity of this code? And also Is there a good way to reduce loops? • Looks like a Plus + to me, guess it's just semantics.... – ArtisticPhoenix Mar 22 at 14:35 • good way to reduce loops yes str_repeat and chunk_split you can see this example (a code golf answer I did) of what you can do with these 2, codegolf.stackexchange.com/questions/171679/… basically you could make one long string with the space or * by using str_repeat and then split it into rows with chunk_split – ArtisticPhoenix Mar 22 at 14:45 • Thanks, @ArtisticPhoenix, I have seen it but didn't get any logic because of the code in a single line. – Gufran Hasan Mar 22 at 14:50 • For example function f($n){$s='';$b=str_pad('*',($m=$n*2+1),' ',2);for($i=0;$i<$m;++$i)$s.=($i==$n)?str_repeat('*',$m):$b;return chunk_split($s, $m);} Sandbox – ArtisticPhoenix Mar 22 at 14:56 • It looks nice. Can you please make me understand how it works. – Gufran Hasan Mar 22 at 14:59 ## 2 Answers It looks nice. Can you please make me understand how it works For example  function f($n){$s='';$b=str_pad('*',($m=$n*2+1),' ',2);for($i=0;$i<$m;++$i)$s.=($i==$n)?str_repeat('*',$m):$b;return chunk_split($s, $m);}  Output  * * * * * *********** * * * *  Sandbox Let me write it in a way that is easier to see $n = 5;
$row_len =$n*2+1;
$output = ''; //pad$n spaces on each side of *
$default = str_pad('*',$row_len,' ',STR_PAD_BOTH); //is = "     *     "

//loop once for each vertical row (same as width)
for($i=0;$i<$row_len;++$i){
if($i==$n){
//do the center line all *'s
$output .= str_repeat('*',$row_len);//is = "***********"
}else{
//use the default line from above
$output .=$default;
}
}

//now we have a single line that is the length squared so we can chunk it
//into equal parts, to make a square
echo chunk_split($output,$row_len);  //is = "     *          *     ***********"


Sandbox

Basically we can create the " * " row by using string pad. Because we can pad spaces on both sides of a * up to the length of a row ($n*2)+1. Then the center row, is just * so we can use string repeat to the length of the row for that line. Last we take our big huge line of spaces and * and split it into chunks (\n) on the length of our row we want. • Hope that helps explain it a bit better. Basically were exploiting the fact that it conforms to a set pattern. So for example we know if $n is 5 to do 5 spaces a star and 5 more spaces ($n*2)+1 So we can just use String Pad for that and pad 5 spaces on each side. String Pad takes the total length of the string you want. So it's the full length of the row. – ArtisticPhoenix Mar 22 at 15:18 • I think your output is skinnier than the OPs. – mickmackusa Mar 26 at 21:05 • @mickmackusa - it is. I didn't put a space between * * the stars. Shouldn't be too hard to fix, but it adds a variable in. So I was too lazy .... lol – ArtisticPhoenix Mar 26 at 21:26 • DEREGISTERED!!!! What have you done, you mad man! What causes a person to do that?!? An occupational requirement? Witness protection? – mickmackusa Apr 15 at 1:58 Here's my array-functional spin on the task. It is not likely to be faster than @ArtisticPhoenix's solution, but it provides the desired output without loop constructs or conditions. ...just different for the sake of being different. The process generates a full-sized array of strings that "looks" like a vertical stroke of asterisks, then replaces the middle element with a horizontal stroke element. Code: (Demo) $size = 7;                                                     // circumference not radius
$vertical = str_pad('*',$size * 2 - 1, ' ', STR_PAD_BOTH);    // row w/ central symbol
$result = array_fill(0,$size, $vertical); // top-to-bottom stroke of symbols$result[$size / 2] = implode(' ', array_fill(0,$size, '*'));  // left-to-right stroke of symbols
echo implode(PHP_EOL, $result);  For improved readability, I've declared the single-use variable $vertical.

Output: (highlight the text with your cursor to see that the pattern has no unnecessary trailing spaces in any line.)

      *
*
*
* * * * * * *
*
*
*


*notice that I am not bothering to floor() the "horizontal stroke" element key, because php casts float keys to integers. https://www.php.net/manual/en/language.types.array.php