using ctypes methods in python gives unexpected error

Question

I'm pretty new to python and ctypes. I'm trying to accomplish a seemingly easy task but am getting unexpected results. I'm trying to pass a string to a c function so I'm using the c_char_p type but it's giving me an error message. To simply it, this is whats happening:

>>>from ctypes import *
>>>c_char_p("hello world") 
 Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: string or integer address expected instead of str instance

What's going on here?

Does this answer your question? Python 3.5, ctypes: TypeError: bytes or integer address expected instead of str instance — gre_gor
– gre_gor, Commented Nov 20, 2023 at 10:55

Santa · Accepted Answer · 2011-12-12 20:36:06Z

8

In Python 3.x, the "text literal" is really a unicode object. You want to use the byte-string literal like b"byte-string literal"

>>> from ctypes import *
>>> c_char_p('hello world')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: string or integer address expected instead of str instance
>>> c_char_p(b'hello world')
c_char_p(b'hello world')
>>>

answered Dec 12, 2011 at 20:36

Santa

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1 Comment

Brandon Yates Over a year ago

Thank you this helps very much. Turns out I was looking at python 2.7 documentation which is why I was so confused.

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