一.c，ctypes和python的数据类型的对应关系

ctypes type ctype Python type

c_char char 1-character string

c_wchar wchar_t 1-character unicode string

c_byte char int/long

c_ubyte unsigned char int/long

c_short short int/long

c_ushort unsigned short int/long

c_int int int/long

c_uint unsigned int int/long

c_long long int/long

c_ulong unsigned long int/long

c_longlong __int64 or long long int/long

c_ulonglong unsigned __int64 or unsigned long long int/long

c_float float float

c_double double float

c_char_p char * (NUL terminated) string or None

c_wchar_p wchar_t * (NUL terminated) unicode or None

c_void_p void * int/long or None

2.操作int

>>> from ctypes import *

>>> c=c_int(34)

>>> c

c_int(34)

>>> c.value

34

>>> c.value=343

>>> c.value

343

3.操作字符串

>>> p=create_string_buffer(10)

>>> p.raw

'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

>>> p.value='fefefe'

>>> p.raw

'fefefe\x00\x00\x00\x00'

>>> p.value='fefeeeeeeeeeeeeeeeeeeeeeee'  #字符串太长，报错

Traceback (most recent call last):

File "", line 1, in

ValueError: string too long

4.操作指针

>>> i=c_int(999)

>>> pi=pointer(i)

>>> pi

>>> pi.value

Traceback (most recent call last):

File "", line 1, in

AttributeError: 'LP_c_int' object has no attribute 'value'

>>> pi.contents

c_int(999)

>>> pi.contents=c_long(34343)

>>> pi.contents

c_int(34343)

通过pointer获取一个值的指针

通过contents获取一个指针的值

5.c的结构体

#定义一个c的structure，包含两个成员变量x和y

>>> class POINT(Structure):

...     _fields_=[('x',c_int),('y',c_int)]

...

>>> point=POINT(2,4)

>>> point

>>> point.x,point.y

(2, 4)

>>> porint=POINT(y=2)

>>> porint

>>> point=POINT(y=2)

>>> point.x,point.y

(0, 2)

定义一个类型为POINT的数组

>>> POINT_ARRAY=POINT*3

>>> pa=POINT_ARRAY(POINT(2,3),POINT(2,4),POINT(2,5))

>>> for i in pa:print pa.y

...

Traceback (most recent call last):

File "", line 1, in

AttributeError: 'POINT_Array_3' object has no attribute 'y'

>>> for i in pa:print i.y

...

3

4

5

6.访问so文件

1).创建一个c文件

#include

int hello_world(){

printf("Hello World\n");

return 0;

}

int main(){

hello_world();

return 0;

}

2).编译成动态链接库

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