php 删除无意义的空行，移动文件指针

# 删除无意义的空行
$str = preg_replace("/\r/", "\n", $str);

#替换\n前面的空白字符为\n，然后把多个\n只留一个
$str = preg_replace("/\s+\n/", "\n", $str);

$str = preg_replace("/\t/"," ",$str);
$str = preg_replace(array("'</head[^>]*?>.*?<'si",), array('</head><',), $str);
echo $str;

# "r"只读方式打开，指针指向文件头
$fp = fopen($fn, 'r');
$pos = 440;

# 把指针向后跳440字符
fseek($fp, $pos, SEEK_CUR);

# 读取当前行内容
$title = fgets($fp);