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How can ctypes be used to obtain the type and size of `time_t`?

asked 2021-10-20 11:00:00 +0000

nofretete gravatar image

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answered 2022-03-06 03:00:00 +0000

plato gravatar image

One possible way to use ctypes to obtain the type and size of time_t is to define a dummy C function that takes a time_t argument and uses the sizeof operator to obtain the size of time_t. Here's an example of how to do this:

import ctypes

# Define a dummy C function that takes a time_t argument
_libc = ctypes.cdll.LoadLibrary('libc.so.6')
_libc.time.restype = ctypes.c_long
_libc.time.argtypes = [ctypes.c_void_p]

# Call the dummy function with a NULL pointer to obtain the size of time_t
time_t_size = _libc.time(ctypes.c_void_p())

# Print the type and size information
print(f'time_t is {ctypes.c_long.__name__} ({ctypes.sizeof(ctypes.c_long)} bytes)')
print(f'time_t size is {time_t_size} bytes')

Note that this code assumes that libc.so.6 is present and provides a time function that takes a time_t argument. It also assumes that time_t is typedef-ed as a long in the system's time.h header file. If these assumptions are not valid for a particular system, the code may need to be adapted accordingly.

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Asked: 2021-10-20 11:00:00 +0000

Seen: 11 times

Last updated: Mar 06 '22