我将首先指出 ctypes 官方文档：[Python 3.5]：ctypes-
Python的外部函数库。
我定义了一个更复杂的结构树（2个嵌套级别）。
data_types.py ：
import ctypesPRAGMA_PACK = 0class Struct2(ctypes.Structure): if PRAGMA_PACK: _pack_ = PRAGMA_PACK _fields_ = [ ("c_0", ctypes.c_char), # 1B ("s_0", ctypes.c_short), # 2B ("wanted", ctypes.c_int), # 4B ]class Struct1(ctypes.Structure): if PRAGMA_PACK: _pack_ = PRAGMA_PACK _fields_ = [ ("d_0", ctypes.c_double), # 8B ("c_0", ctypes.c_char), # 1B ("struct2_0", Struct2), ]class Struct0(ctypes.Structure): if PRAGMA_PACK: _pack_ = PRAGMA_PACK _fields_ = [ ("i_0", ctypes.c_int), # 4B ("s_0", ctypes.c_short), # 2B ("struct1_0", Struct1), ]注意事项 ：
- 我命名了 想要 的感兴趣的成员（ Struct2的 一部分，这是最深的成员）
- 处理 struct 时，重要的一件事是 对齐 。检查[MSDN]：#pragma pack以获得更多详细信息。
为了说明第二个项目符号（上面），我准备了一个小例子（与问题无关）。
test_addressof.py ：
import sysimport ctypesimport data_typesOFFSET_TEXT = "Offset of '{:s}' member in '{:s}' instance: {:3d} (0x{:08X})"def offset_addressof(child_structure_instance, parent_structure_instance): return ctypes.addressof(child_structure_instance) - ctypes.addressof(parent_structure_instance)def print_offset_addressof_data(child_structure_instance, parent_structure_instance): offset = offset_addressof(child_structure_instance, parent_structure_instance) print(OFFSET_TEXT.format(child_structure_instance.__class__.__name__, parent_structure_instance.__class__.__name__, offset, offset))def main(): s0 = data_types.Struct0() s1 = s0.struct1_0 s2 = s1.struct2_0 print("PRAGMA_PACK: {:d} {:s}n".format(data_types.PRAGMA_PACK, "" if data_types.PRAGMA_PACK else "(default)")) print_offset_addressof_data(s1, s0) print_offset_addressof_data(s2, s1) print_offset_addressof_data(s2, s0) print("nAlignments and sizes:nt'{:s}': {:3d} - {:3d}nt'{:s}': {:3d} - {:3d}nt'{:s}': {:3d} - {:3d}".format( s0.__class__.__name__, ctypes.alignment(s0), ctypes.sizeof(s0), s1.__class__.__name__, ctypes.alignment(s1), ctypes.sizeof(s1), s2.__class__.__name__, ctypes.alignment(s2), ctypes.sizeof(s2) ) ) #print("Struct0().i_0 type: {:s}".format(s0.i_0.__class__.__name__))if __name__ == "__main__": print("Python {:s} on {:s}n".format(sys.version, sys.platform)) main()注意事项 ：
- 本机 C 成员类型在中转换为 Python 类型，如果接收到这样的参数
ctypes.Structure
，ctypes.addressof
则会引发 TypeError （检查来自 main 的注释 打印 ） __ - 我试图在各种 *** 作系统 上使用大小相同的 C 类型（例如，我避免在 Lnx上 长8个字节，在 Win上 长4个字节（当然，谈论64位版本））
ctypes.c_long
__ - 在两个示例运行之间需要对源进行修改。我本来可以动态生成类，但是这会给代码增加不必要的复杂性（并远离我要提出的观点）
输出 ：
(py35x64_test) e:WorkDevStackOverflowq050304516>pythontest_addressof.py
Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit
(AMD64)] on win32PRAGMA_PACK: 0 (default)Offset of 'Struct1' member in 'Struct0' instance: 8 (0x00000008)Offset of 'Struct2' member in 'Struct1' instance: 12 (0x0000000C)Offset of 'Struct2' member in 'Struct0' instance: 20 (0x00000014)Alignments and sizes: 'Struct0': 8 - 32 'Struct1': 8 - 24 'Struct2': 4 - 8(py35x64_test) e:WorkDevStackOverflowq050304516>rem changePRAGMA_PACK = 1 in data_types.py
(py35x64_test) e:WorkDevStackOverflowq050304516>pythontest_addressof.py
Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit
(AMD64)] on win32PRAGMA_PACK: 1Offset of 'Struct1' member in 'Struct0' instance: 6 (0x00000006)Offset of 'Struct2' member in 'Struct1' instance: 9 (0x00000009)Offset of 'Struct2' member in 'Struct0' instance: 15 (0x0000000F)Alignments and sizes: 'Struct0': 1 - 22 'Struct1': 1 - 16 'Struct2': 1 - 7
struct_util.py ：
import sysimport ctypesimport data_typesWANTED_MEMBER_NAME = "wanted"FIELDS_MEMBER_NAME = "_fields_"def _get_padded_size(sizes, align_size): padded_size = temp = 0 for size in sizes: if temp >= align_size: padded_size += temp temp = size elif temp + size > align_size: padded_size += align_size temp = size else: temp += size if temp: padded_size += max(size, align_size) return padded_sizedef _get_array_type_sizes(array_type): if issubclass(array_type._type_, ctypes.Array): return _get_array_type_sizes(array_type._type_) * array_type._type_._length_ else: return [array_type._type_] * array_type._length_def get_nested_offset_recursive(struct_instance, wanted_member_name): if not isinstance(struct_instance, ctypes.Structure): return -1 align_size = ctypes.alignment(struct_instance) base_address = ctypes.addressof(struct_instance) member_sizes = list() for member_name, member_type in getattr(struct_instance, FIELDS_MEMBER_NAME, list()): if member_name == wanted_member_name: return _get_padded_size(member_sizes, align_size) if issubclass(member_type, ctypes.Structure): nested_struct_instance = getattr(struct_instance, member_name) inner_offset = get_nested_offset_recursive(nested_struct_instance, wanted_member_name) if inner_offset != -1: return ctypes.addressof(nested_struct_instance) - base_address + inner_offset else: member_sizes.append(ctypes.sizeof(member_type)) else: if issubclass(member_type, ctypes.Array): member_sizes.extend(_get_array_type_sizes(member_type)) else: member_sizes.append(ctypes.sizeof(member_type)) return -1def _get_struct_instance_from_name(struct_name): struct_class = getattr(data_types, struct_name, None) if struct_class: return struct_class()def get_nested_offset(struct_name, wanted_member_name): struct_instance = _get_struct_instance_from_name(struct_name) return get_nested_offset_recursive(struct_instance, wanted_member_name)def main(): struct_names = [ "Struct2", "Struct1", "Struct0" ] wanted_member_name = WANTED_MEMBER_NAME print("PRAGMA_PACK: {:d} {:s}n".format(data_types.PRAGMA_PACK, "" if data_types.PRAGMA_PACK else "(default)")) for struct_name in struct_names: print("'{:s}' offset in '{:s}' (size: {:3d}): {:3d}".format(wanted_member_name, struct_name, ctypes.sizeof(_get_struct_instance_from_name(struct_name)), get_nested_offset(struct_name, wanted_member_name)))if __name__ == "__main__": print("Python {:s} on {:s}n".format(sys.version, sys.platform)) main()注意事项 ：
- 代码比我最初预期的要复杂得多。我认为有一种更简单的方法，但是我看不到它。希望我不会错过这么明显的地方，以至于整个事情可以用2-3行代码完成
- 它应该适用于任何结构，尽管有很多我没有测试过的案例（尤其是结构数组，其中有些案例是行不通的）
- 它将在找到的第一个成员出现时停止
- 功能（1比1）：
- get_nested_offset_recursive- 核心功能：在结构中递归搜索成员并计算其偏移量。有两种情况：
- 构件是在一个 子 结构（或 孩子 的 孩子 ，…）：偏移到 子 结构通过减去2个结构地址计算（使用
ctypes.addressof
） - 成员处于当前结构中（复杂情况）：考虑到偏移量之前的成员大小以及结构对齐方式来计算偏移量
- __get_padded_size- 尝试将成员大小（在我们关注的大小之前）放入 _align_size 大块中，并返回块大小和
- __get_array_type_sizes- 数组不是 _原子的 （来自对齐 PoV ）：
char c[10];
成员可以替换为char c0, c1, ..., c9;
。这是此函数的作用（递归） - __get_struct_instance_from_ name- 帮助程序或便利函数：返回作为参数给出的结构名称的实例（在 _data_types 模块中搜索）
- get_nested_offset- 包装器函数
输出 （与上述原理相同）：
(py35x64_test) e:WorkDevStackOverflowq050304516>pythonstruct_util.py
Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit
(AMD64)] on win32PRAGMA_PACK: 0 (default)'wanted' offset in 'Struct2' (size: 8): 4'wanted' offset in 'Struct1' (size: 24): 16'wanted' offset in 'Struct0' (size: 32): 24(py35x64_test) e:WorkDevStackOverflowq050304516>rem changePRAGMA_PACK = 1 in data_types.py
(py35x64_test) e:WorkDevStackOverflowq050304516>pythonstruct_util.py
Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit
(AMD64)] on win32PRAGMA_PACK: 1'wanted' offset in 'Struct2' (size: 7): 3'wanted' offset in 'Struct1' (size: 16): 12'wanted' offset in 'Struct0' (size: 22): 18
@ EDIT0 ：
正如我在1指定的ST和（特别是）的2本笔记，我是不满意的解决方案，主要是因为即使它的工作电流的情况下，它不为一般一个（嵌套数组和结构）。然后我遇到了[SO]：Ctypes：获取一个指向struct字段的指针（@MarkTolonen的答案），并采取了另一种方法。
data_types.py （ 将 以下代码 添加 到先前的内容中）：
class Struct0_1(ctypes.Structure): if PRAGMA_PACK: _pack_ = PRAGMA_PACK _fields_ = [ ("i_0", ctypes.c_int), # 4B ("s_0", ctypes.c_short), # 2B ("struct1_0_2", Struct1 * 2), ("i_1", ctypes.c_int * 2), # 2 * 4B ("struct1_1", Struct1), ("i_2", ctypes.c_int), # 4B ("struct1_2_3", Struct1 * 3), ]struct_util_v2.py ：
import sysimport ctypesimport data_typesWANTED_MEMBER_NAME = "wanted"def _get_nested_offset_recursive_struct(struct_ctype, member_name): for struct_member_name, struct_member_ctype in struct_ctype._fields_: struct_member = getattr(struct_ctype, struct_member_name) offset = struct_member.offset if struct_member_name == member_name: return offset else: if issubclass(struct_member_ctype, ctypes.Structure): inner_offset = _get_nested_offset_recursive_struct(struct_member_ctype, member_name) elif issubclass(struct_member_ctype, ctypes.Array): inner_offset = _get_nested_offset_recursive_array(struct_member_ctype, member_name) else: inner_offset = -1 if inner_offset != -1: return inner_offset + offset return -1def _get_nested_offset_recursive_array(array_ctype, member_name): array_base_ctype = array_ctype._type_ for idx in range(array_ctype._length_): if issubclass(array_base_ctype, ctypes.Structure): inner_offset = _get_nested_offset_recursive_struct(array_base_ctype, member_name) elif issubclass(array_base_ctype, ctypes.Array): inner_offset = _get_nested_offset_recursive_array(array_base_ctype, member_name) else: inner_offset = -1 return inner_offsetdef get_nested_offset_recursive(ctype, member_name, nth=1): if issubclass(ctype, ctypes.Structure): return _get_nested_offset_recursive_struct(ctype, member_name) elif issubclass(ctype, ctypes.Array): return _get_nested_offset_recursive_array(ctype, member_name) else: return -1def main(): struct_names = [ "Struct2", "Struct1", "Struct0", "Struct0_1", ] member_name = WANTED_MEMBER_NAME print("PRAGMA_PACK: {:d} {:s}n".format(data_types.PRAGMA_PACK, "" if data_types.PRAGMA_PACK else "(default)")) for struct_name in struct_names: struct_ctype = getattr(data_types, struct_name) print("'{:s}' offset in '{:s}' (size: {:3d}): {:3d}".format(member_name, struct_name, ctypes.sizeof(struct_ctype), get_nested_offset_recursive(struct_ctype, member_name)))if __name__ == "__main__": print("Python {:s} on {:s}n".format(sys.version, sys.platform)) main()注意事项 ：
- 由于偏移量元数据存储在类本身中，因此不再需要使用实例（ 地址 不再需要）
- 对于新添加的结构，以前的代码不起作用
- 新代码的真正力量在于处理 get_nested_offset_recursive 的第 n个 参数（该参数现在什么都不做-可以删除），该参数 指示 应报告成员名称的哪个偏移量（仅对结构数组有意义），但这有点复杂，因此需要更多代码
- 值得争论的可能是结构成员是指向结构的指针（有些人可能会争辩说将它们视为数组），但是我认为，由于这样的（内部）结构位于另一个内存区域中，因此只需跳过它们即可（事实上代码使用起来更简单）这种方法与决定无关）
输出 ：
(py35x64_test) e:WorkDevStackOverflowq050304516>pythonstruct_util_v2.py
Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit
(AMD64)] on win32PRAGMA_PACK: 0 (default)'wanted' offset in 'Struct2' (size: 8): 4'wanted' offset in 'Struct1' (size: 24): 16'wanted' offset in 'Struct0' (size: 32): 24'wanted' offset in 'Struct0_1' (size: 168): 24(py35x64_test) e:WorkDevStackOverflowq050304516>rem changePRAGMA_PACK = 1 in data_types.py
(py35x64_test) e:WorkDevStackOverflowq050304516>pythonstruct_util_v2.py
Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit
(AMD64)] on win32PRAGMA_PACK: 1'wanted' offset in 'Struct2' (size: 7): 3'wanted' offset in 'Struct1' (size: 16): 12'wanted' offset in 'Struct0' (size: 22): 18'wanted' offset in 'Struct0_1' (size: 114): 18
@ EDIT1 ：
添加了对 第n个 参数的支持（将其重命名为： index ）。
struct_util_v3.py ：
import sysimport ctypesimport data_typesWANTED_MEMBER_NAME = "wanted"OFFSET_INVALID = -1def _get_nested_offset_recursive_struct(struct_ctype, member_name, index): current_index = 0 for struct_member_name, struct_member_ctype in struct_ctype._fields_: struct_member = getattr(struct_ctype, struct_member_name) offset = struct_member.offset if struct_member_name == member_name: if index == 0: return offset, 0 else: current_index += 1 else: if issubclass(struct_member_ctype, ctypes.Structure): inner_offset, occurences = _get_nested_offset_recursive_struct(struct_member_ctype, member_name, index - current_index) elif issubclass(struct_member_ctype, ctypes.Array): inner_offset, occurences = _get_nested_offset_recursive_array(struct_member_ctype, member_name, index - current_index) else: inner_offset, occurences = OFFSET_INVALID, 0 if inner_offset != OFFSET_INVALID: return inner_offset + offset, 0 else: current_index += occurences return OFFSET_INVALID, current_indexdef _get_nested_offset_recursive_array(array_ctype, member_name, index): array_base_ctype = array_ctype._type_ array_base_ctype_size = ctypes.sizeof(array_base_ctype) current_index = 0 for idx in range(array_ctype._length_): if issubclass(array_base_ctype, ctypes.Structure): inner_offset, occurences = _get_nested_offset_recursive_struct(array_base_ctype, member_name, index - current_index) elif issubclass(array_base_ctype, ctypes.Array): inner_offset, occurences = _get_nested_offset_recursive_array(array_base_ctype, member_name, index - current_index) else: inner_offset, occurences = OFFSET_INVALID, 0 if inner_offset != OFFSET_INVALID: return array_base_ctype_size * idx + inner_offset, 0 else: if occurences == 0: return OFFSET_INVALID, 0 else: current_index += occurences return OFFSET_INVALID, current_indexdef get_nested_offset_recursive(ctype, member_name, index=0): if index < 0: return OFFSET_INVALID if issubclass(ctype, ctypes.Structure): return _get_nested_offset_recursive_struct(ctype, member_name, index)[0] elif issubclass(ctype, ctypes.Array): return _get_nested_offset_recursive_array(ctype, member_name, index)[0] else: return OFFSET_INVALIDdef main(): struct_names = [ "Struct2", "Struct1", "Struct0", "Struct0_1", ] member_name = WANTED_MEMBER_NAME print("PRAGMA_PACK: {:d} {:s}n".format(data_types.PRAGMA_PACK, "" if data_types.PRAGMA_PACK else "(default)")) for struct_name in struct_names: struct_ctype = getattr(data_types, struct_name) nth = 1 ofs = get_nested_offset_recursive(struct_ctype, member_name, index=nth - 1) while ofs != OFFSET_INVALID: print("'{:s}' offset (#{:03d}) in '{:s}' (size: {:3d}): {:3d}".format(member_name, nth, struct_name, ctypes.sizeof(struct_ctype), ofs)) nth += 1 ofs = get_nested_offset_recursive(struct_ctype, member_name, index=nth - 1)if __name__ == "__main__": print("Python {:s} on {:s}n".format(sys.version, sys.platform)) main()注意事项 ：
- get_nested_offset_recursive 的 指标 参数是（ 0 基于在成员出现列表）指数-或多少次报告抵消之前跳过（默认值： 0 -这意味着它会报告1日印发生的）
- 没有彻底测试，但我认为我涵盖了所有情况
- 对于每个结构，程序都会列出所有成员出现的偏移量（直到找不到它）
- 现在，代码的形状就像我一开始所想的
输出 ：
(py35x64_test) e:WorkDevStackOverflowq050304516>pythonstruct_util_v3.py
Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit
(AMD64)] on win32PRAGMA_PACK: 0 (default)'wanted' offset (#001) in 'Struct2' (size: 8): 4'wanted' offset (#001) in 'Struct1' (size: 24): 16'wanted' offset (#001) in 'Struct0' (size: 32): 24'wanted' offset (#001) in 'Struct0_1' (size: 192): 24'wanted' offset (#002) in 'Struct0_1' (size: 192): 48'wanted' offset (#003) in 'Struct0_1' (size: 192): 72'wanted' offset (#004) in 'Struct0_1' (size: 192): 104'wanted' offset (#005) in 'Struct0_1' (size: 192): 136'wanted' offset (#006) in 'Struct0_1' (size: 192): 160(py35x64_test) e:WorkDevStackOverflowq050304516>rem changePRAGMA_PACK = 1 in data_types.py
(py35x64_test) e:WorkDevStackOverflowq050304516>pythonstruct_util_v3.py
Python 3.5.4 (v3.5.4:3f56838, Aug 8 2017, 02:17:05) [MSC v.1900 64 bit
(AMD64)] on win32PRAGMA_PACK: 1'wanted' offset (#001) in 'Struct2' (size: 7): 3'wanted' offset (#001) in 'Struct1' (size: 16): 12'wanted' offset (#001) in 'Struct0' (size: 22): 18'wanted' offset (#001) in 'Struct0_1' (size: 130): 18'wanted' offset (#002) in 'Struct0_1' (size: 130): 34'wanted' offset (#003) in 'Struct0_1' (size: 130): 50'wanted' offset (#004) in 'Struct0_1' (size: 130): 74'wanted' offset (#005) in 'Struct0_1' (size: 130): 94'wanted' offset (#006) in 'Struct0_1' (size: 130): 110
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