我认为您可能缺少的是确切地知道您希望分配结构内存的位置。下面的c代码提供了一个为struct分配内存并返回指向它的指针的函数(new_struct())。#include
#include
#include
typedef struct {
int a;
int b;
} my_struct;
my_struct *new_struct()
{
my_struct *struct_instance = (my_struct *)malloc(sizeof(my_struct));
memset(struct_instance, 0, sizeof(my_struct));
return struct_instance;
}
int modify_struct(my_struct *ms) {
ms->a = 1;
ms->b = 2;
return 0;
}
void print_struct_c(my_struct *ms) {
printf("my_struct {\n"
" a = %d\n"
" b = %d\n"
"}\n", ms->a, ms->b);
}
从Python获取指针,调用执行分配的C函数,然后可以将其传递给将其作为参数的其他C函数。import ctypes
lib_file_path = <<< path to lib file >>>
# Very simple example of how to declare a ctypes structure to twin the
# C library's declaration. This doesn't need to be declared if the Python
# code isn't going to need access to the struct's data members.
class MyStruct(ctypes.Structure):
_fields_ = [('a', ctypes.c_int),
('b', ctypes.c_int)]
def print_struct(s):
# Print struct that was allocated via Python ctypes.
print("my_struct.a = %d, my_struct.b = %d" % (s.a, s.b))
def print_struct_ptr(sptr):
# Print pointer to struct. Note the data members of the pointer are
# accessed via 'contents'.
print("my_struct_ptr.contents.a = %d, my_struct_ptr.contents.b = %d"
% (sptr.contents.a, sptr.contents.b))
my_c_lib = ctypes.cdll.LoadLibrary(lib_file_path)
# If you don't need to access the struct's data members from Python, then
# it's not necessary to declare MyStruct above. Also, in that case,
# 'restype' and 'argtypes' (below) can be set to ctypes.c_void_p instead.
my_c_lib.new_struct.restype = ctypes.POINTER(MyStruct)
my_c_lib.modify_struct.argtypes = [ctypes.POINTER(MyStruct)]
# Call C function to create struct instance.
my_struct_c_ptr = my_c_lib.new_struct()
print_struct_ptr(my_struct_c_ptr)
my_c_lib.modify_struct(my_struct_c_ptr)
print_struct_ptr(my_struct_c_ptr)
# Allocating struct instance from Python, then passing to C function.
my_struct_py = MyStruct(0, 0)
print_struct(my_struct_py)
my_c_lib.modify_struct(ctypes.byref(my_struct_py))
print_struct(my_struct_py)
# Data members of Python allocated struct can be acessed directly.
my_struct_py.a = 555
my_c_lib.print_struct_c(ctypes.byref(my_struct_py)) # Note use of 'byref()'
# to invoke c function.
上面的代码已经更新,包括如何通过Python分配结构实例的示例,以及如何访问C已分配或Python分配结构的数据成员(请注意打印函数中的差异)。