os.py

python的典型方法,对初学的python的人有一定的借鉴作用。

import os
from operator import sub,add
from random import randint, choice
ops = {'+' : add, '-' : sub}
MAXTRIES = 2

def doprob():
	op = choice('+-')
	nums = [(randint(1, 10)) for x in range(2)]
	nums.sort(reverse=True)
	ans = ops[op](*nums)
	pr = "%d %s %d =" % (nums[0], op, nums[1])
	oops = 0
	while True:
		try:
			if int(raw_input(pr)) == ans:
				print "Correct"
				break
			if (oops == MAXTRIES):
				print 'Answer: %s%d' %(pr, ans)
			else:
				print 'incorrect...try again'
				oops += 1
		except (KeyboardInterrupt,EOFError,ValueError):
			print 'invalid input...try again'
def main():
	while True:
		doprob()
		try:
			opt = raw_input('Again?[y]:').lower()
			if opt and opt[0] == 'n':
				break
		except (KeyboardInterrupt,EOFError):
			break
if __name__=='__main__':
	main()