Python print 输出到文件

Python3.x

#!/usr/bin/env python3
#coding:utf-8
year = 1
years = 5
bj = 10000
rate = 0.05
f = open("./source/interest.bak", 'w+')
while year < years:
    bj = bj * (1 + rate)
    print("第{0}年,本金息总计{1}".format(year, bj), file=f)
    year += 1

Python2.x

#!/usr/bin/env python
#coding:utf-8
year = 1
years = 15
bj = 10000
rate = 0.05
f = open("./source/interest.bak", 'w+')
while year < years:
    bj = bj * (1 + rate)
    print >> f, "第%d年,本金息总计%0.2f" % (year, bj)
    year += 1