CODEWITHSUNDEEP
pythonprintfctypes
Kev
Kev

Reputation: 313

Python3k ctypes printf

printf returns 1 instead of "Hello World!" which is the desired result.

I googled it and think its because of the changes in the way sequences are treated.

How do I modify the code to print "Hello World!"?

www.mail-archive.com/[email protected]/msg15119.html

import ctypes

msvcrt=ctypes.cdll.msvcrt
string=b"Hello World!"
msvcrt.printf("%s", string)

Upvotes: 2

Views: 3053

Answers (1)

interjay
interjay

Reputation: 110108

The first argument needs to be a byte string as well:

msvcrt.printf(b"%s", string)

The return value of printf is the number of characters printed, which should be 12 in this case.

Edit:

If you want the string to be returned instead of printed, you can use sprintf instead. This is dangerous and NOT recommended.

s = ctypes.create_string_buffer(100)   #must be large enough!!
msvcrt.sprintf(s, b'%s', b'Hello World!')
val = s.value

I don't know why you'd want to do this though, since Python has its own string formatting. sprintf is a dangerous method since it is susceptible to buffer overflows.

Upvotes: 4

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