日常记录-2021.7.1

1. python读取二进制是bytes流，通过 “rb” 和 "wb"读取。struct中有pack、unpack等函数可以处理。字节流是多少不一定，看怎么读取。

# 字节翻转
import struct

with open("upload.php", "rb") as f:
    fw = open('desktop.zip', 'wb')
    while True:
        strb = f.read(1)
        if not strb:
            break
        val = struct.unpack("B", strb)[0] # B代表unsigned int(8 bits)
        v = ((val & 0xf0) >> 4) + ((val & 0xf) << 4)
        s = struct.pack('B', v)
        fw.write(s)
    fw.close()

3. bytes.encode() 转换为str str.decode()转换为bytes