今天写了段猜数字记录record的代码如下：

<span style="font-family:Microsoft YaHei;font-size:14px;">#!/usr/bin/env python
#-*- coding:utf-8 -*-

f = open('c:\py\guess_number_record.txt','r')
record = f.read().split()
game_times = int(record[0])
min_times = int(record[1])
total_times = int(record[2])

if game_times > 0:
    avg_times = float(total_times/game_times)
else:
    avg_times = 0
</span><pre name="code" class="python"><span style="font-family: 'Microsoft YaHei'; font-size: 14px;">    #avg_times = float(0) 正确写法</span>

总是报错

Traceback (most recent call last):
  File "guess.py", line 15, in <module>
    print('你已经玩了{0}次游戏，最快{1}轮猜出，总共猜了{2}轮，平均{3:.3}轮猜出。'.format(game_times,min_times,total_times,avg_times))
ValueError: Precision not allowed in integer format specifier

提示说有效数字的精确度不允许用在整形的格式转换上，因为对浮点数的format转换不太熟练，将print语句中的{3:.3}改为{3},程序运行正常。于是找avg_times跟int有关的地方，发现else语句中avg_times被赋值为0，此处avg_times被赋值为int型，与后面的有效数字精确度的format转换冲突，改为avg_times = float(0) 后程序运行正常。