Convert an int value to unicode

Question

I am using pyserial and need to send some values less than 255. If I send the int itself the the ascii value of the int gets sent. So now I am converting the int into a unic

Answer 1

Use the chr() function instead; you are sending a value of less than 256 but more than 128, but are creating a Unicode character.

The unicode character has to then be encoded first to get a byte character, and that encoding fails because you are using a value outside the ASCII range (0-127):

>>> str(unichr(169))
Traceback (most recent call last):
  File "", line 1, in 
UnicodeEncodeError: 'ascii' codec can't encode character u'\xa9' in position 0: ordinal not in range(128)

This is normal Python 2 behaviour; when trying to convert a unicode string to a byte string, an implicit encoding has to take place and the default encoding is ASCII.

If you were to use chr() instead, you create a byte string of one character and that implicit encoding does not have to take place:

>>> str(chr(169))
'\xa9'

Another method you may want to look into is the struct module, especially if you need to send integer values greater than 255:

>>> struct.pack('!H', 1000)
'\x03\xe8'

The above example packs an integer into a unsigned short in network byte order, for example.