php，file操作，怎样实现一个readInt和readUTF

比如我的writeInt和writeUTF是这样

    function write_int($value)
    {
        $data = pack('N', $value);
        fwrite($this->file, $data);
    }

    function write_utf($value)
    {
        $this->write_int(strlen($value));
        fwrite($this->file,$value);
    }

readInt和readUTF怎么实现？

我尝试写，但是类型不对

   function read_int()
    {
        $data = fread($this->file, 4);
        return unpack('N', $data);
    }

    function read_utf($value)
    {
        $l = $this->read_int();#unpack返回一个array不是int
        return fread($this->file,$l);#类型不对
    }

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http://blog.csdn.net/guotong1988/article...