python读写csv文件

#!/usr/bin/python
# -*- coding: UTF-8 -*-
import csv

def writer ():
    aa = csv.writer(file('z.csv', 'wb'))
    aa.writerow(['c1', 'c2', 'c3'])
    lines = [range(3) for i in range(5)]
    for a in lines:
        aa.writerow(a)

def reader ():
    bb = csv.reader(file('z.csv', 'rb'))
    for b in bb:
        print b

if __name__ == '__main__':
    writer()
    reader()