("ii", a, b)
print 'length:', len(str) #length: 8
print str
print repr(str) # '/x14/x00/x00/x00/x90/x01...'/x14/x00/x00/x00/x90/x01/x00/x00'
===== pack_into - unpack_from =====
'/x00/x00/x00/x00/x00/x00/x00/...x00/x00/x00/x00/x00'
'/x01/x00/x00/x00/x02/x00/x00/x00/xff/xff/xff/xff'
(1, 2, -1)
==================...print str # 乱码:
print repr(str) # '\x14\x00\x00\x00\x90\x01...x00\x00\x00\x00\x00\x00\x00'
struct.pack_into("iii", buf, 0, 1, 2, -1)
print repr(buf.raw) # '\x01