Python调用C库

Python可以利用ctypes库很方便地调用C的库函数。 C库例程：

# file: a.c

int sum(int a, int b){

  int t = 0;

  int i = 0;

  for(; i < b;i++) t += a;

  return t;

}

shell> gcc -fPIC -g -c -Wall a.c && gcc -shared -Wl,-soname,liba.so -o liba.so a.o

  Python程序例程：

# file: a.py

import timeit

n=1000000

def s(a,b):

  t = 0

  for i in xrange(b):

    t += a

  return t

print s(10,100)

t = timeit.Timer("s(10,20)", "from __main__ import s")

print t.timeit(n)

del s

import ctypes

a = ctypes.cdll.LoadLibrary("./liba.so")

s = a.sum

print s(10,100)

t = timeit.Timer("s(10,20)", "from __main__ import s")

print t.timeit(n)

  运行比较：

shell> python2.6 a.py

1000

1.94600701332

1000

0.611714839935