PHP prints a solid and hollow diamond with side length N

php prints a solid and hollow rhombus with side length N

Solid rhombus calculation method:

$n: side length
$i: current line, starting from 0
$rows: Total number of rows

Upper
Number of preceding spaces =$n-$i-1
Number of characters =$i*2+1
Lower
Number of preceding spaces =$i-$n+1
Number of characters =($rows-$i)*2-1

Using str_pad can reduce for/while loops

/**
 * 打印实心菱型
 * @param  int    $n 边长,默认5
 * @param  String $s 显示的字符, 默认*
 * @return String
 */
function solidDiamond($n=5, $s='*'){

    $str = '';

    // 计算总行数
    $rows = $n*2-1;

    // 循环计算每行的*
    for($i=0; $i<$rows; $i++){
        if($i<$n){ // 上部
            $str .= str_pad(&#39;&#39;, ($n-$i-1), &#39; &#39;). str_pad(&#39;&#39;, $i*2+1, $s)."\r\n";
        }else{     // 下部
            $str .= str_pad(&#39;&#39;, ($i-$n+1), &#39; &#39;). str_pad(&#39;&#39;, ($rows-$i)*2-1, $s). "\r\n";
        }
    }

    return $str;

}

echo &#39;<xmp>';
echo solidDiamond(5);
echo '</xmp>';

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

Hollow diamond calculation method:
$n: side length
$i: current row, starting from 0
$rows: total number of rows
upper part
number of preceding spaces=$n-$i-1
number of empty spaces=$i*2+1-2
number of characters=$i* 2+1 - Number of empty spaces
lower part
number of front spaces=$i-$n+1
number of empty spaces=($rows-$i)*2-1-2
number of characters=($rows-$ i)*2-1 - Number of empty spaces

/**
 * 打印空心菱型
 * @param  int    $n 边长,默认5
 * @param  String $s 显示的字符, 默认*
 * @return String
 */
function hollowDiamond($n=5, $s='*'){

    $str = '';

    // 计算总行数
    $rows = $n*2-1;

    // 循环计算每行的*
    for($i=0; $i<$rows; $i++){
        if($i<$n){ // 上部
            $tmp = $i*2+1;
            $str .= str_pad(&#39;&#39;, ($n-$i-1), &#39; &#39;). str_pad(str_pad(&#39;&#39;, $tmp-2, &#39; &#39;, STR_PAD_BOTH), $tmp, $s, STR_PAD_BOTH)."\r\n";
        }else{     // 下部
            $tmp = ($rows-$i)*2-1;
            $str .= str_pad(&#39;&#39;, ($i-$n+1), &#39; &#39;). str_pad(str_pad(&#39;&#39;, $tmp-2, &#39; &#39;, STR_PAD_BOTH), $tmp, $s, STR_PAD_BOTH). "\r\n";
        }
    }

    return $str;

}

echo &#39;<xmp>';
echo hollowDiamond(5);
echo '</xmp>';

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

The above introduces PHP to print a solid and hollow diamond shape with side length N, including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.