I'd like to resize a ctypes array. As you can see, ctypes.resize doesn't work like it could. I can write a function to resize an array, but I wanted to know some other solutions to this. Maybe I'm missing some ctypes trick or maybe I simply used resize wrong. The name c_long_Array_0 seems to tell me this may not work with resize.
>>> from ctypes import *
>>> c_int * 0
<class '__main__.c_long_Array_0'>
>>> intType = c_int * 0
>>> foo = intType()
>>> foo
<__main__.c_long_Array_0 object at 0xb7ed9e84>
>>> foo[0]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: invalid index
>>> resize(foo, sizeof(c_int * 1))
>>> foo[0]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: invalid index
>>> foo
<__main__.c_long_Array_0 object at 0xb7ed9e84>
>>> sizeof(c_int * 0)
0
>>> sizeof(c_int * 1)
4
Edit: Maybe go with something like:
>>> ctypes_resize = resize
>>> def resize(arr, type):
... tmp = type()
... for i in range(len(arr)):
... tmp[i] = arr[i]
... return tmp
...
...
>>> listType = c_int * 0
>>> list = listType()
>>> list = resize(list, c_int * 1)
>>> list[0]
0
>>>
But that's ugly passing the type instead of the size. It works for its purpose and that's it.
from ctypes import *
list = (c_int*1)()
def customresize(array, new_size):
resize(array, sizeof(array._type_)*new_size)
return (array._type_*new_size).from_address(addressof(array))
list[0] = 123
list = customresize(list, 5)
>>> list[0]
123
>>> list[4]
0
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