php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;$j++)          //控制每一行的空格个数
                      {
                              echo" ";
                       }
                       for($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 " ";
            }
            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";

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