python struct

   calcsize(fmt)
      　　fmt为格式化字符串,返回格式化字符串所占字节大小
　　　　　 比如fmt=">5sH" calcsize(fmt)　输出7 5s２个字节，H2个字节


    pack(fmt, v1, v2, ...)
　　　　按fmt将v1,v2格式化存储并返回一个字符串

   pack_into(fmt, buffer, offset, v1, v2, ...)
        pack完的数据存放到buffer中偏移offset的位置，offset必须指定

    unpack(fmt, string)
        Unpack the string containing packed C structure data, according to fmt.
        Requires len(string) == calcsize(fmt).

    unpack_from(fmt,content,offset)
　　　　　　按fmt中格式从context偏移offset处解析出tuple对象

　　　　　　Unpack the buffer, containing packed C structure data, according to fmt,
　　　　　　 starting at offset. Requires len(buffer[offset:]) >= calcsize(fmt).
　　

搬砖整理

fmt:来自python帮助文档

The optional first format char indicates byte order, size and alignment: 

  @: native order, size & alignment (default)
  =: native order, std. size & alignment
  <: little-endian, std. size & alignment
  >: big-endian, std. size & alignment
  !: same as >

import struct

#----------------------------------------------------------------------
def main():
    """"""
    fmt =     ">5sH"
    pbuf  = struct.pack(fmt,"11111",1)
    open("1.txt","wb").write(pbuf)

    
    readbuf=open("1.txt","rb").read()
    tp=struct.unpack(fmt,readbuf)

    for i in tp:
        print i


if __name__ == '__main__':

    main()

输出: