python+ c/c++ 混编

示例：

https://www.cnblogs.com/pyse/p/8590829.html

修改示例(结构体：包含指针的联合体)：

test1.py

#pycall.pyimport ctypes
from ctypes import *

class private_u(Union):
    _fields_ = [("string" , c_char_p),
                ("integer", c_longlong),
                ("boolean", c_bool),
                ("floating", c_double)
                ]  



class Student(Structure):
    _fields_ = [("name",c_char * 30),
                ("fScore", c_int * 3),
                ("data", private_u)
                ]    

su = Student()
su.name = b"test-sdk"
PARAM = c_int * 3
fScore = PARAM()
fScore[0] = 55
fScore[1] = 33
fScore[2] = 51
a = private_u()
a.integer =39
su.data   =a

su.fScore = fScore

if __name__ == '__main__':
    
    ll = cdll.LoadLibrary   
    lib = ll("./libpycall.so") 
    # lib.Display.restype = c_float
    lib.Display.argtypes = [Student]   #这一行很重要 
    lib.Display(su)  
    print('----- finish -----')
    a.string = 'abcdefghij'.encode("utf-8")
    su.data   =a 
    lib.Display.argtypes = [Student]   #这一行很重要 
    lib.Display(su) 
    print('----- finish 1-----')
    a.floating = 39.21111111111111111
    su.data   =a 
    lib.Display.argtypes = [Student]   #这一行很重要 
    lib.Display(su) 
    print('----- finish 2-----')
    a.boolean = True
    su.data   =a 
    lib.Display.argtypes = [Student]   #这一行很重要 
    lib.Display(su) 
    

test1.c

//test1.c
# include <stdio.h>
# include <stdlib.h>
# include <stdbool.h>

union private_u{
        char *string;               
        long long integer;              
        bool boolean;               
        double floating;            
    };
//创建一个Student结构体 
struct Student
{
    char name[30];
    int fScore[3];
    union private_u data;
};

void Display(struct Student su)
{
    printf("-----Information------\n");
    printf("Name:%s\n",su.name);
    printf("Chinese:%d\n",su.fScore[0]);
    printf("Math:%d\n",su.fScore[1]);
    printf("English:%d\n",su.fScore[2]);
    printf("总分数为:%d\n", su.fScore[0]+su.fScore[1]+su.fScore[2]);
    printf("平均分数为:%d\n",((su.fScore[0]+su.fScore[1]+su.fScore[2]))/3);
   // printf("data.string:%s\n",su.data.string);
    printf("data.integer:%d\n",su.data.integer);
    printf("data.boolean:%d\n",su.data.boolean);
    printf("data.floating:%f\n",su.data.floating);
}

/*
struct attr_value {
    union {
            char *string;               
            int64 integer;              
            bool boolean;               
            double floating;            
        } private_u;
};

*/

version2: 传入通用数据并进行赋值

test1.py

#pycall.pyimport ctypes
from ctypes import *

class private_u(Union):
    _fields_ = [("string" , c_char_p),
                ("integer", c_longlong),
                ("boolean", c_bool),
                ("floating", c_double)
                ]  



class Student(Structure):
    _fields_ = [("name",c_char_p),
                ("data", private_u)
                ]    

su = Student()
#su.name = b"test-sdk"
a = private_u()


if __name__ == '__main__':
    
    ll = cdll.LoadLibrary   
    lib = ll("./libpycall.so") 
    # lib.Display.restype = c_float
    lib.Display.argtypes = [Student]   #这一行很重要 
    lib.fun()

    su.name = "aa".encode("utf-8")   
    a.integer =39
    su.data   =a
    lib.Display(su)  

    su.name = "bb".encode("utf-8")   
    a.string ="this a char var".encode("utf-8") 
    su.data   =a
    lib.Display(su)  

    

test1.cc

g++ -o libpycall.so -shared -fPIC test1.cc

//test1.c
# include <stdio.h>
# include <stdlib.h>
# include <stdbool.h>
#include<string>
#include<vector>
using namespace std;

union private_u{
        char *string;               
        long long integer;              
        bool boolean;               
        double floating;            
    };
//创建一个Student结构体 
struct Student
{
    char *name;
    union private_u data;
};

int aa;
char* bb;

struct var{
    char *name;
    private_u* ptr;
};
vector<var> vars;
#if defined(__cplusplus)
extern "C" {
#endif
void fun(){
    var v1={"aa", (private_u*)&aa};
    vars.push_back(v1);
    var v2={"bb", (private_u*)&bb};
    vars.push_back(v2);
}



void Display(struct Student su)
{

    printf("-----Information------\n");
    printf("Name:%s\n",su.name);
    for(auto &a:vars){
        printf("a.name:%s\n",a.name);
        std::string str1 = a.name;
        std::string str2 = su.name;
        if(str1 ==str2){      
           *(a.ptr) =su.data;
        }
    }
    printf("aa:%d\n",aa);
    printf("bb:%s\n",bb);
    //printf("aa:%d\n",su.data.integer);

}
#if defined(__cplusplus)
}
#endif

输出：

-----Information------
Name:aa
a.name:aa
a.name:bb
aa:39
bb:(null)
-----Information------
Name:bb
a.name:aa
a.name:bb
aa:39
bb:this a char var

test1.cc:使用map提升查找效率

//test1.c
# include <stdio.h>
# include <stdlib.h>
# include <stdbool.h>
#include<string>
#include<vector>
#include<map>
using namespace std;

union private_u{
        char *string;               
        long long integer;              
        bool boolean;               
        double floating;            
    };
//创建一个Student结构体 
struct Student
{
    char *name;
    union private_u data;
};

int aa;
char* bb;

struct var{
    char *name;
    private_u* ptr;
};
//vector<var> vars;
map<string , private_u* > vars;
#if defined(__cplusplus)
extern "C" {
#endif
void fun(){
    // var v1={"aa", (private_u*)&aa};
    // vars.push_back(v1);
    // var v2={"bb", (private_u*)&bb};
    // vars.push_back(v2);

    vars["aa"]=(private_u*)&aa;
    vars["bb"]=(private_u*)&bb; 
}



void Display(struct Student su)
{

    printf("-----Information------\n");
    printf("Name:%s\n",su.name);
    // for(auto &a:vars){
    //     printf("a.name:%s\n",a.name);
    //     std::string str1 = a.name;
    //     std::string str2 = su.name;
    //     if(str1 ==str2){      
    //        *(a.ptr) =su.data;
    //     }
    // }
    std::string str = su.name;
    *(vars[str]) =su.data;

    printf("aa:%d\n",aa);
    printf("bb:%s\n",bb);
    //printf("aa:%d\n",su.data.integer);

}
#if defined(__cplusplus)
}
#endif

详解：

使用 ctypes 进行 Python 和 C 的混合编程：

https://www.cnblogs.com/gaowengang/p/7919219.html

补充：

python与C结构体之间数据转换：

https://www.cnblogs.com/iclodq/p/9216763.html

python3调用c函数接口的错误：

TypeError: bytes or integer address expected instead of str instance

utf8转换（OK了）：

net = dn.load_net("cfg/yolov3.cfg".encode("utf-8"), "weights/yolov3.weights".encode("utf-8"), 0)