Paragraph 2 content. . . Paragraph 2 content. . . Paragraph 2 content. . . Paragraph 2 content. . .Paragraph 2 content. . .

Requirement is to have different back ground color for both the paragraphs . . it s easy if you have only two paragraphs but in practical purpose a page may contains 10-15 paragraph and then arises the problem.

Codes:
The idea is to add a division class before each paragraph. An odd class before odd paragraphs and even class before even paragraph.

<?php
  function replace_different($search,$replace,$content) {
    $occs = substr_count($content,$search);
    $last = 0;
    $cur = 0;
    $data = '';
    for ($i=0;$i<$occs;$i++) {
      $find = strpos($content,$search,$last);
      $data .= substr($content,$last,$find-$last).$replace[$cur];
      $last = $find+strlen($search);
      if (++$cur == count($replace)) {
        $cur = 0;
      }
    }
    return $data.substr($string,$last);
  }

echo replace_different('<p>',array('<p class="podd">','<p class="peven">'),$content);
?>

Now define peven and podd in your base.css file