参考来源：https://www.cnblogs.com/yssjun/p/9960479.html
直观例子：
import ctypes, platform, time
if platform.system() == 'Windows':
libc = ctypes.cdll.LoadLibrary('msvcrt.dll')
elif platform.system() == 'Linux':
libc = ctypes.cdll.LoadLibrary('libc.so.6')
print libc
Example 1
libc.printf('%s
', 'lib c printf function')
libc.printf('%s
', ctypes.c_char_p('lib c printf function with c_char_p'))
libc.printf('%ls
', ctypes.c_wchar_p(u'lib c printf function with c_wchar_p'))
libc.printf('%d
', 12)
libc.printf('%f
', ctypes.c_double(1.2))
Example 2
libc.sin.restype = ctypes.c_double
print libc.sin(ctypes.c_double(30 * 3.14 / 180))
Example 3
libc.pow.restype = ctypes.c_double
print libc.pow(ctypes.c_double(2), ctypes.c_double(10))
Example 4
print libc.time(), time.time()
Example 5
libc.strcpy.restype = ctypes.c_char_p
res = 'Hello'
print libc.strcpy(ctypes.c_char_p(res), ctypes.c_char_p('World'))
print res