Deeply understand several PHP algorithms :PHP bubble PHP dichotomy PHP prime PHP multiplication table

PHP several algorithm collation involves the following examples.
PHP bubbling
PHP2 points method
Prime PHP o
PHP multiplication table

Example of PHP bubble method

//PHP The bubbling    Since the childhood 
function maopao(&$arr)
{
  if(!empty($arr))
  {
    for($i=0;$i<count($arr);$i++)
      {
        if($arr[$i]>$arr[$j])
        {
          // Began to exchange 
          $temp = $arr[$i];
          $arr[$i] = $arr[$j];
          $arr[$j] = $temp;
        }
      }
    }
    return $arr;
  }
}

php2 points to find code examples

//2 Points method lookup 
function erfenfa($a,$arr)
{
  print_r($arr);
  if(!empty($a)  &&  !empty($arr))
  {
    $start = 0;
    $end = count($arr)-1;
    $i = 0;
    while($start <= $end)     {
                        $i ++;
                        $step = floor($end / 2);
                       if($a == $arr[$step])
                       {
                        print_r($arr[$step]);
                     return $a;
                     }
                     if($a >$arr[$step])
      {
        $start = $step;
      }
      if($a &lt; $arr[$step])
      {
        $end = $step;
      }
    }
  }
}

The primes at php count between a and b. Code sample

//php For prime   -  To calculate  a  to  b  Between the prime Numbers. 
function sushu($a,$b)
{
  if(!empty($a) && !empty($b))
  {
    if($b<$a) return;
    $temp = array();
    for($i=$a;$i <=$b;$i++)
    {
      $j = intval(sqrt($i));
      $flag = true;
      if($i&lt;=3)
      {
        $temp[$i] = $i;
      }else
      {
        for($x=2;$x<=$j;$x++)
        {
          if($i%$x==0)
          {
            $flag = false;
            break;
          }
        }
        if($flag)
        {
          $temp[$i] = $i;
        }
      }
    }
    return $temp;
  }
}

PHP output times table - recursive code example

//PHP Output multiplication table - recursive 
function digui($a,$step)
{
  if($a >$step) return;
  if( !empty($a) &&  !empty($step) )
  {
    for($i=1;$i<=$a;$i++)
    {
      echo $i.'*'.$a.'='.$a*$i. " \t " ;
      if($i == $a )  echo  ' 
 ' ;
    }
    $a = $a + 1;
    digui($a,$step);
  }
}

PHP output multiplication table - loop code example

//PHP Output multiplication table - cycle 
function chengfa($a,$step)
{
  if( !empty($a) && !empty($step) )
  {
    for($i=$a;$i<=$step;$i++)
    {
      for($j=1;$j<=$i;$j++)
      {
        echo $j.'*'.$i.'='.$i*$j. " \t " ;
        if($i==$j) echo  ' 
 ' ;
      }
    }
  }
}