python - ctypes.cast 总是抛出 ArgumentError

Question

我有以下代码

 from ctypes import cast, c_char_p, c_int, byref, POINTER

 # ...
 mj, mn, pt = c_int(), c_int(), c_int()
 // FreeType
 __dll__.FT_Library_Version(__handler__, byref(mj), byref(mn), byref(pt))

 print("{0}.{1}.{2}".format(cast(mj, POINTER(c_char_p).value, cast(mn, POINTER(c_char_p).value, cast(pt, POINTER(c_char_p)).value)

抛出一个ArgumentError来自cast功能ctypes.ArgumentError: argument 1: <class 'TypeError'>: wrong type

问题是为什么？我的代码中的错误在哪里我是 ctypes 的新手，但我找到了类似 cast(c_int, POINTER(c_char_p)) 的示例用于 pŕint c_int没有得到c_int(2)

Answer 1

来自文档:

The cast() function can be used to cast a ctypes instance into a pointer to a different ctypes data type. cast() takes two parameters, a ctypes object that is or can be converted to a pointer of some kind, and a ctypes pointer type. It returns an instance of the second argument, which references the same memory block as the first argument.

我想你只是想这样做:

print("%d.%d.%d"%(mj.value,mn.value,pt.value))