Python ctypes库底层交互秘籍实例探究

from ctypes import CDLL, c_int
# 加载C标准库
libc = CDLL("libc.so.6")  # 示例加载 C 库
# 加载Windows DLL
kernel32 = CDLL("kernel32.dll")

# 在C标准库中调用printf函数
printf = libc.printf
printf(b"Hello, %s\n", b"World")

# 用c_int表示整数类型
my_int = c_int(42)

# 定义结构体
from ctypes import Structure, c_int

class Point(Structure):
    _fields_ = [("x", c_int), ("y", c_int)]

# 使用结构体
point = Point(10, 20)

from ctypes import Union, c_int, c_double

# 定义联合体
class NumberUnion(Union):
    _fields_ = [("i", c_int), ("d", c_double)]

# 使用联合体
number = NumberUnion()
number.i = 42
print(number.d)  # 输出42.0

from ctypes import CFUNCTYPE, c_int

# 定义回调函数类型
callback_func = CFUNCTYPE(c_int, c_int, c_int)

# 在C函数中使用Python回调函数
def my_callback(a, b):
    return a + b

c_function_that_needs_callback = some_library.function_requiring_callback
c_function_that_needs_callback.argtypes = (callback_func,)
c_function_that_needs_callback.restype = c_int

from ctypes import CFUNCTYPE, c_int

# 定义不同签名的函数类型
func_type1 = CFUNCTYPE(c_int, c_int)
func_type2 = CFUNCTYPE(c_int, c_int, c_int)

# 在运行时更改函数类型
function_pointer = cast(some_function_pointer, func_type2)

# 在Windows上调用MessageBox函数
from ctypes import WinDLL

user32 = WinDLL('user32')
user32.MessageBoxW(None, 'Hello, ctypes!', 'Message', 0)

# 调用libpng中的函数
from ctypes import cdll

libpng = cdll.LoadLibrary("libpng.so")
# 调用libpng函数...