ctypes使用

有关定义：

(1)__declspec(dllexport)

导出函数，即指明该函数可从DLL中调用

(2)__declspec(dllimport)

导入函数（ctypes尚没有碰到对他的具体应用）

#define EXPORT __declspec(dllexport)
EXPORT int IntAdd(int a, int b)
{
	return a + b;
}

EXPORT char *hello_python()
{
	//char p[] = "hi python, this is c speaking...";
	char *p = "hi python, this is c speaking...";
	return p;
}

先C中写两个函数，以供ctypes调用：

from ctypes import *

filename = 'test_ctypes.dll'
dll = cdll.LoadLibrary(filename)

然后就可以通过dll对象来调用C代码中的“导出函数(__declspec(dllexport))”

intadd = dll.IntAdd
intadd .argtypes设置传入参数的类型

例：addint.argtypes = [c_int, c_int]

intadd .restype设置返回类型

例：addint.restype = c_int

有参数值或者返回值时，应当指明其类型

dll = cdll.LoadLibrary(filename)
addint = dll.IntAdd
addint.argtypes = [c_int, c_int]
addint.restype = c_int
print addint(1,2)#3

print dll.IntAdd(1,2)#3 结果同样也是3，type类型为int，但如果C语言中参数及返回值类型变为了float类型此处就会出现问题

对于只有返回值而没有入参的函数：

只需设定其返回值类型

str_fun = dll.hello_python
str_fun.restype = c_char_p
print str_fun()# hi python, this is c speaking...

ctypes的数据类型映射

ctypes type	C type	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_bool	bool	bool
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 longlong	int/long
c_ulonglong	unsigned __int64 or unsigned long long	int/long
c_float	float	float
c_double	double	float
c_longdouble	long double float	float
c_char_p	char *	string or None
c_wchar_p	wchar_t *	unicode or None
c_void_p	void *	int/long or None