问传递.h文件中定义的结构指针的Python C类型。

EN

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

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);
}

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.