php写二进制文件

<?php
/*
    二进制文件格式如下
    +-----------------------------------------------------+
    |总记录数(4B)|空白(7B)--------------------------------|
    |开始ip(4B) |结束ip(4B) |省id(1B)|市id(1B)|ispid(1B)|
    |开始ip(4B) |结束ip(4B) |省id(1B)|市id(1B)|ispid(1B)|
    |开始ip(4B) |结束ip(4B) |省id(1B)|市id(1B)|ispid(1B)|
    +-----------------------------------------------------+
*/
//要写如的文件

$filename="a.dat";
//wb表示用二进制重新写文件

$fp=fopen($filename,'wb')or die("cannot open a.dat");
//原始数据:开始ip,结束ip,省id,市id,isp的id

$records=array(
                  array(
                          '110.25.23.1', //开始ip

                          '110.25.23.254', //结束ip

                          3, //省id

                          1, //市id

                          6 //isp的id

                       ),
                  array(
                          '210.200.10.1',
                          '210.254.23.254',
                          1,
                          1,
                          2
                       ),
                 array(
                          '211.68.154.1',
                          '211.254.47.254',
                          2,
                          2,
                          2
                       ),

                                    array(
                          '222.22.45.1',
                          '254.255.255.255',
                          3,
                          3,
                          3
                       ),
                  array(
                          '255.255.255.255',
                          '255.255.255.255',
                          0,
                          0,
                          0
                       )
              );

//计算记录总数

$total=count($records);
//用4个字节记录记录总数

$inputstr=sprintf("%08x",$total);
echo "$inputstr";
//用4个字节记录记录总数，写入文件

$str=pack ("H8",$inputstr);
fwrite($fp,$str);

 //补充7个字节的空白

$str=pack ("a7","");
fwrite($fp,$str);
foreach($records as $item)
{
    //用4个字节记录开始ip

    $inputstr=sprintf("%x",ip2long($item[0]));
    $str=pack ("H8",$inputstr);
    fwrite($fp,$str);

        //用4个字节记录结束ip

    $inputstr=sprintf("%x",ip2long($item[1]));
    $str=pack ("H8",$inputstr);
    fwrite($fp,$str);

    //用1个字节记录省id

    $inputstr=sprintf("%02x",$item[2]);
    $str=pack ("H2",$inputstr);
    fwrite($fp,$str);

    //用1个字节记录市id

    $inputstr=sprintf("%02x",$item[3]);
    $str=pack ("H2",$inputstr);
    fwrite($fp,$str);

        //用1个字节记录ispid

    $inputstr=sprintf("%02x",$item[4]);
    $str=pack ("H2",$inputstr);
    fwrite($fp,$str);
}
fclose($fp);


?>