11.3. 使用二进制数据记录布局

struct 模块为使用变长的二进制记录格式提供了 pack() 和 unpack() 函数。下面的示例演示了在不使用 zipfile 模块的情况下如何迭代一个 ZIP 文件的头信息。压缩码 "H" 和 "I" 分别表示2和4字节无符号数字， " 表明它们都是标准大小并且按照 little-endian 字节排序。 ~~~ import struct with open('myfile.zip', 'rb') as f: data = f.read() start = 0 for i in range(3): # show the first 3 file headers start += 14 fields = struct.unpack(', data[start:start+16]) crc32, comp_size, uncomp_size, filenamesize, extra_size = fields start += 16 filename = data[start:start+filenamesize] start += filenamesize extra = data[start:start+extra_size] print(filename, hex(crc32), comp_size, uncomp_size) start += extra_size + comp_size # skip to the next header ~~~