我正在使用 pyOpenGL，OpenGL 要求我通过传递指针和要传输的字节数来传输数据。
我知道 python 不像 c 那样在内存中存储变量。我找到了使我的程序运行的以下代码:
x = [1, 2, ... ] # some list
(ctypes.c_int * len(x))(*x)
但是我不知道它为什么会起作用(而且我不想相信我并没有因为一切都落入内存而幸运)。这段代码实际上在做什么？
请您参考如下方法:
The recommended way to create concrete array types is by multiplying any ctypes data type with a positive integer. Alternatively, you can subclass this type and define length and type class variables. Array elements can be read and written using standard subscript and slice accesses; for slice reads, the resulting object is not itself an Array.
Example:
>>> from ctypes import * >>> TenIntegers = c_int * 10 >>> ii = TenIntegers(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) >>> print ii <c_long_Array_10 object at 0x...> >>> for i in ii: print i, ... 1 2 3 4 5 6 7 8 9 10 >>>
因此，第一部分 ctypes.c_int * len(x) 创建了一个包含 len(x) 元素的数组类型:
In [17]: ctypes.c_int * 10
Out[17]: __main__.c_int_Array_10
In [18]: ctypes.c_int * 100
Out[18]: __main__.c_int_Array_100
创建类型后，您应该调用它并传递数组元素:
(ctypes.c_int * len(x))(*x)
# ^^^^
创建的数组类型接受可变数量的元素，因此，您应该 expand list x using the *x form :
In [24]: x = [1, 2, 3]
In [25]: (ctypes.c_int * len(x))(*x)
Out[25]: <__main__.c_int_Array_3 at 0x7f0b34171ae8>
In [26]: list((ctypes.c_int * len(x))(*x))
Out[26]: [1, 2, 3]
In [27]: (ctypes.c_int * len(x))(*x)[1]
Out[27]: 2
您不能传递 x，因为 __init__ 需要整数:
In [28]: (ctypes.c_int * len(x))(x)
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-28-ff45cb7481e4> in <module>()
----> 1 (ctypes.c_int * len(x))(x)
TypeError: an integer is required (got type list)
