python3 中调用 C 语言的函数

python3 中调用 C 语言的函数

一， 先用 C 语言写好一个函数库

my_math.c

#include
int add(int num1, int num2)
{
	return num1 + num2;
}

int sub(int num1, int num2)
{
	return num1 - num2;
}

int mul(int num1, int num2)
{
	return num1 * num2;
}

int div(int num1, int num2)
{
	return num1 / num2;
}

二， 然后使用 gcc 编译成动态库

gcc -c -fPIC my_math.c
gcc -shared my_math.o -o my_math.so

三， 使用 python 的 ctypes 库导入该静态库

#!/opt/python3/bin/python3
#
from ctypes import *
import os

print("begin ......")
libmathpath = os.path.join(os.getcwd(),"math.so")
print(libmathpath)
libmath = CDLL(libmathpath)
print("-----------------")
print(" ADD: 21 89")
print(libmath.add(21,89))
print("-----------------")
print(" SUB: 124 89")
print(libmath.sub(123,89))
print("-----------------")
print(" MUL: 12 77")
print(libmath.mul(12,77))
print("-----------------")
print(" DIV: 183 3")
print(libmath.div(183,3))
print("-----------------")

4， 执行结果如下：

begin ......
/home/git/math.so
-----------------
 ADD: 21 89
110
-----------------
 SUB: 124 89
34
-----------------
 MUL: 12 77
924
-----------------
 DIV: 183 3
61
-----------------

如图 1（math.c 源码）
如图 2（testmath.py）源码
如图 3（执行结查）

. /opt/fsl-imx-xwayland/5.4-zeus/environment-setup-aarch64-poky-linux
$CC  -c -fPIC my_math.c
$CC -shared my_math.o -o my_math.so

scp my_math.so root@192.168.99.46:/home/root/

/home/root/my_math.so

>>> from ctypes import *
>>> import os
>>> libmath = CDLL("/home/root/my_math.so")
>>> print(libmath.add(21,89))
110
>>> print(libmath.sub(123,89))
34
>>> libmath.mul(12,77)
924
>>> libmath.div(183,3)
61
>>>

环境ubuntu 16.04 python3
https://blog.csdn.net/MrCheny/article/details/79022973
1.pycall.c

#include 
#include 
struct test
{
        int key;
        char* val;
};
 
//传递数值
int ValTest(int n)
{
        printf("val:%dn", n);
        return 0;
}
 
//传递字符串
int strTest(char* pVal)
{
        printf("val:%sn", pVal);
        return 0;
}
 
//传递结构体
int StructTest(struct test data)
{
        printf("key:%d,val:%sn", data.key, data.val);
        return 0;
}
 
//传递结构体指针
int PointTest(struct test* pData)
{
        printf("key:%d,val:%sn", pData->key, pData->val);
        return 0;
}
 
//传递数组
int szTest(int a[], int nLen)
{
        for(int i = 0; i < nLen; i++)
        {
                printf("%d ", a[i]);
        }
        printf("n");
        return 0;
}

11

$CC  -c -fPIC pycall.c
$CC -shared pycall.o -o pycall.so

scp pycall.so root@192.168.99.46:/home/root/

2.pycall.py

# -*- coding: utf8 -*-
 
import ctypes
from ctypes import *
 
print ('*' * 20)
print ("传递数字")
func = ctypes.cdll.LoadLibrary("./pycall.so")
func.ValTest(2)
 
print ('*' * 20)
print ("传递字符串")
val = bytes('qqqqqq',encoding='utf-8')
func.strTest(val)
 
print ('*' * 20)
print ("传递结构体")
class testStruct(Structure):
        _fields_=[('key',c_int),('val',c_char_p)]
 
s = testStruct()
s.key = 1
s.val = bytes('test',encoding='utf-8');
func.StructTest(s)
 
print ('*' * 20)
print ("传递结构体指针")
func.PointTest(byref(s))
 
print ('*' * 20)
print ("传递数组")
INPUT = c_int * 10
data = INPUT()
for i in range(10):
        data[i] = i
 
func.szTest(data,len(data))
print ('*' * 20)

python3 pycall.py

********************
传递数字
val:2
********************
传递字符串
val:qqqqqq
********************
传递结构体
key:1,val:test
********************
传递结构体指针
key:1,val:test
********************
传递数组
0 1 2 3 4 5 6 7 8 9
********************

https://docs.python.org/3.6/library/ctypes.html#structures-and-unions

https://blog.51cto.com/u_15329836/3413057

#include 

//extern "C"
//{
//  void intList(int numList[]);
//}

void intList(int numList[])
{
  int i ;
  for(i= 0 ; i< 10; i++){
    printf("%d %dn",i,numList[i]);

  }

  for(i =0; i< 10; i++){

     numList[i] = i ;
  }
}

gcc -c -fPIC list_test.c
gcc -shared list_test.o -o list_test.so

from ctypes import *
dllObj = CDLL('./list_test.so')

numList = (c_int * 10)(99,66,55,88,33,22)

dllObj.intList(numList)

for i in numList:
   print(i)

python3 list_test.py
运行结果:

0 99
1 66
2 55
3 88
4 33
5 22
6 0
7 0
8 0
9 0
0
1
2
3
4
5
6
7
8
9

https://blog.csdn.net/sinat_22510827/article/details/123435081