输出正立金字塔

<?php

    $a = 10;
     function zjt($a)                                               //定义一个函数zjt()
         {
                global $a;
                for($i = 1;$i <= $a;$i++ )                    //控制输出的行数
                {
                       for($j = 1;$j<= $a -$i;$j++)          //控制每一行的空格个数
                       {
                               echo"&nbsp";
                        }
                        for($k = 1;$k <= $i;$k++)         //控制每行*号个数
                       {
                            echo "* ";
                        }
                        echo "<br>";
                  }
         }
          zjt($a);                                                    //调用函数zjt()




    $a = 20;
    function dzjt($a)                                          // 定义了一个dzjt（）的函数
    {
        global $a;
        for($i = 1;$i <= $a;$i++)                          // 控制输出的行数
        {
            for($j = 1;$j < $i;$j++)                         //控制每行输出的空格数
            {
                 echo "&nbsp";
             }
             for($k = 1;$k <=$a + 1 -$i;$k++)         //控制每行输出的*号数
            {
                echo "* ";
             }
             echo "<br>";
          }
     }
     dzjt($a);*/                                                  //调用djzt( )函数





    echo '1~100的素数：';
    for($i = 2;$i <= 100;$i++)
    {
          $a = 1;                              //用$a的值来表示$i是否能被其他数（除了1和本身）整除
          for($j = 2;$j < $i;$j++)
          {
               if($i % $j == 0)
              {
                    $a = 0;                   //$a=0，能被其他数整除
                    break;
               }
          }
           if($a == 1)                       //$a=1，表示是素数
           {
                echo $i." " ;
            }
     }






    echo '1~100的素数之和:'
    $sum = 0;
    for($i = 2;$i <= 100;$i++)
        {
             $a = 1;
             for($j = 2;$j < $i;$j++)
            {
                   if($i % $j == 0)
                   {
                        $a = 0;
                        break;
                   }
              }
          if($a == 1)
          {
              $sum = $sum + $i;
          }
      }
   echo "$sum";