如何在Python3 TCP/IP 通信中 只发送一个字节

SmileN

大家好，请教大家一个问题，如何在Python3的TCP/IP连接中，只发送一个字节
我的代码如下：

1. import socket
   
2. import sys
   
3. import struct
   
4. import ctypes
   
5. 
   
6. 
   
7. host = '128.64.6.103'
   
8. port = 37000
   
9. 
   
10. address = (host, port)  
    
11. s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    
12. sa = (host, port)
    
13. s.connect(sa)
    
14. 
    
15. if s is None:
    
16.     print ('could not open socket! ')
    
17.     sys.exit(1)
    
18. 
    
19. 
    
20. cmd_word = 0xC0
    
21. tx_buf = struct.pack('<I', cmd_word)
    
22. print(repr(tx_buf))
    
23. s.send(tx_buf)

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但是每次都发送了四个字节
打印出来的时候

1. >>>
   
2. b'\xc0\x00\x00\x00'

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我尝试过 I 改成 c 或者 x 均报错，请问如何才能发送定长的1个字节 ，谢谢！

SmileN

被我一个个的试出来了

1. import socket
   
2. import sys
   
3. import struct
   
4. import ctypes
   
5. 
   
6. 
   
7. host = '128.64.6.103'
   
8. port = 37000
   
9. 
   
10. address = (host, port)  
    
11. s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    
12. sa = (host, port)
    
13. s.connect(sa)
    
14. 
    
15. if s is None:
    
16.     print ('could not open socket! ')
    
17.     sys.exit(1)
    
18. 
    
19. 
    
20. cmd_word = int(0xC0)
    
21. print(type(cmd_word))
    
22. tx_buf = struct.pack('>B', cmd_word)
    
23. print(repr(tx_buf))
    
24. s.send(tx_buf)

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打印的结果

1. >>>
   
2. <class 'int'>
   
3. b'\xc0'
   
4. >>>

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痛苦的过程

1. Python 3.4.3 (v3.4.3:9b73f1c3e601, Feb 24 2015, 22:44:40) [MSC v.1600 64 bit (AMD64)] on win32
   
2. Type "copyright", "credits" or "license()" for more information.
   
3. >>> ================================ RESTART ================================
   
4. >>>
   
5. b'\xc0\x00\x00\x00'
   
6. >>> ================================ RESTART ================================
   
7. >>>
   
8. Traceback (most recent call last):
   
9.   File "C:\Users\Nevii\Desktop\client.py", line 21, in <module>
   
10.     tx_buf = struct.pack('<c', cmd_word)
    
11. struct.error: char format requires a bytes object of length 1
    
12. >>> ================================ RESTART ================================
    
13. >>>
    
14. Traceback (most recent call last):
    
15.   File "C:\Users\Nevii\Desktop\client.py", line 21, in <module>
    
16.     tx_buf = struct.pack('<b', cmd_word)
    
17. struct.error: byte format requires -128 <= number <= 127
    
18. >>> ================================ RESTART ================================
    
19. >>>
    
20. Traceback (most recent call last):
    
21.   File "C:\Users\Nevii\Desktop\client.py", line 21, in <module>
    
22.     tx_buf = struct.pack('<b', 0xc0)
    
23. struct.error: byte format requires -128 <= number <= 127
    
24. >>> ================================ RESTART ================================
    
25. >>>
    
26. Traceback (most recent call last):
    
27.   File "C:\Users\Nevii\Desktop\client.py", line 21, in <module>
    
28.     tx_buf = struct.pack('<b', 0xc0)
    
29. struct.error: byte format requires -128 <= number <= 127
    
30. >>> ================================ RESTART ================================
    
31. >>>
    
32. Traceback (most recent call last):
    
33.   File "C:\Users\Nevii\Desktop\client.py", line 21, in <module>
    
34.     tx_buf = struct.pack('<ii', 0xc0)
    
35. struct.error: pack expected 2 items for packing (got 1)
    
36. >>> ================================ RESTART ================================
    
37. >>>
    
38. b'\xc0\x00\x00\x00'
    
39. >>> ================================ RESTART ================================
    
40. >>>
    
41. b'\x01\x00\x00\x00\x02\x00\x03'
    
42. (1, 2, 3)
    
43. b'\x00\x00\x00\x01\x00\x02\x03'
    
44. (1, 2, 3)
    
45. >>> ================================ RESTART ================================
    
46. >>>
    
47. Traceback (most recent call last):
    
48.   File "C:\Users\Nevii\Desktop\client.py", line 21, in <module>
    
49.     tx_buf = struct.pack('c', cmd_word)
    
50. struct.error: char format requires a bytes object of length 1
    
51. >>> ================================ RESTART ================================
    
52. >>>
    
53. Traceback (most recent call last):
    
54.   File "C:\Users\Nevii\Desktop\client.py", line 21, in <module>
    
55.     print(len(cmd_word))
    
56. TypeError: object of type 'int' has no len()
    
57. >>> ================================ RESTART ================================
    
58. >>>
    
59. 4
    
60. Traceback (most recent call last):
    
61.   File "C:\Users\Nevii\Desktop\client.py", line 22, in <module>
    
62.     tx_buf = struct.pack('c', cmd_word)
    
63. struct.error: char format requires a bytes object of length 1
    
64. >>> ================================ RESTART ================================
    
65. >>>
    
66. Traceback (most recent call last):
    
67.   File "C:\Users\Nevii\Desktop\client.py", line 21, in <module>
    
68.     type(comd_word)
    
69. NameError: name 'comd_word' is not defined
    
70. >>> ================================ RESTART ================================
    
71. >>>
    
72. Traceback (most recent call last):
    
73.   File "C:\Users\Nevii\Desktop\client.py", line 22, in <module>
    
74.     tx_buf = struct.pack('c', cmd_word)
    
75. struct.error: char format requires a bytes object of length 1
    
76. >>> ================================ RESTART ================================
    
77. >>>
    
78. >>> ================================ RESTART ================================
    
79. >>>
    
80. <class 'int'>
    
81. >>> ================================ RESTART ================================
    
82. >>>
    
83. <class 'int'>
    
84. Traceback (most recent call last):
    
85.   File "C:\Users\Nevii\Desktop\client.py", line 22, in <module>
    
86.     tx_buf = struct.pack('>=c', cmd_word)
    
87. struct.error: bad char in struct format
    
88. >>> ================================ RESTART ================================
    
89. >>>
    
90. <class 'int'>
    
91. Traceback (most recent call last):
    
92.   File "C:\Users\Nevii\Desktop\client.py", line 22, in <module>
    
93.     tx_buf = struct.pack('=>c', cmd_word)
    
94. struct.error: bad char in struct format
    
95. >>> ================================ RESTART ================================
    
96. >>>
    
97. <class 'int'>
    
98. Traceback (most recent call last):
    
99.   File "C:\Users\Nevii\Desktop\client.py", line 22, in <module>
    
100.     tx_buf = struct.pack('=>i', cmd_word)
     
101. struct.error: bad char in struct format
     
102. >>> ================================ RESTART ================================
     
103. >>>
     
104. <class 'int'>
     
105. b'\x00\x00\x00\xc0'
     
106. >>> ================================ RESTART ================================
     
107. >>>
     
108. <class 'int'>
     
109. b'\x00\x00\x00\xc0'
     
110. Traceback (most recent call last):
     
111.   File "C:\Users\Nevii\Desktop\client.py", line 24, in <module>
     
112.     s.send(0xC0)
     
113. TypeError: 'int' does not support the buffer interface
     
114. >>> ================================ RESTART ================================
     
115. >>>
     
116. <class 'int'>
     
117. b'\x00\x00\x00\xc0'
     
118. >>> ================================ RESTART ================================
     
119. >>>
     
120. <class 'int'>
     
121. Traceback (most recent call last):
     
122.   File "C:\Users\Nevii\Desktop\client.py", line 22, in <module>
     
123.     tx_buf = struct.pack('>c', str(cmd_word))
     
124. struct.error: char format requires a bytes object of length 1
     
125. >>> ================================ RESTART ================================
     
126. >>>
     
127. <class 'int'>
     
128. Traceback (most recent call last):
     
129.   File "C:\Users\Nevii\Desktop\client.py", line 22, in <module>
     
130.     tx_buf = struct.pack('>b', cmd_word)
     
131. struct.error: byte format requires -128 <= number <= 127
     
132. >>> ================================ RESTART ================================
     
133. >>>
     
134. <class 'int'>
     
135. Traceback (most recent call last):
     
136.   File "C:\Users\Nevii\Desktop\client.py", line 22, in <module>
     
137.     tx_buf = struct.pack('>b', cmd_word)
     
138. struct.error: byte format requires -128 <= number <= 127
     
139. >>> ================================ RESTART ================================

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ianv

楼主厉害！！！

我是桃川人

怎么不看文档呢？文档说的很详细，有个表格。

SmileN

我是桃川人 发表于 2015-9-30 13:36
怎么不看文档呢？文档说的很详细，有个表格。

:cry 其实是我悟性差，好久才看懂....