变量未定义？答案

【问题标题】：Variable not defined?变量未定义？
【发布时间】：2017-12-22 21:07:11
【问题描述】：

我是 python 的早期初学者，需要一些帮助。游戏的重点是猜测一个数字，如果它不正确，numguesses 加 1。我知道代码效率不高，但我需要它用于项目。代码如下：

import random

from datetime import datetime
answer = random.randint(1, 2)
guess = 0
now = datetime.now()
play = 'y'


print 'Welcome to Hi-Lo'
print 'The current time is: ' '%s-%s-%s' % (now.year, now.month, now.day)

while play != 'n':
while guess != answer:
    guess =  int(input('Pick a number inbewteen 1-100 to see if its higher or lower:'))
    if guess == answer:
        numguesses = numguesses + 1
        print 'You are correct! The number was: ' + str(answer)
        print 'It took ' + str(numguesses) + ' guess(es)'
    elif guess > answer:
        print 'Too high'
    else:
        print 'Too low'

play = str(input('Play again? [y/n]?'))

它产生的错误是：

Traceback (most recent call last):
  File "C:-----------------------------.py", line 17, in <module>
numguesses = numguesses() + 1

NameError: name 'numguesses' 未定义

因此，如果有人可以对此提供简单的解释，我将不胜感激。谢谢！

【问题讨论】：

numguesses 从来没有初始值，那怎么加1呢？在 while 循环之前，您需要 numguesses = 0。
错误信息与脚本中的行不匹配。为什么numguesses后面有()？
while play != 'n'的正文还需要缩进
如果您刚开始使用 Python，并且在 Windows 上，为了您的理智，请立即安装 Python 3！

标签： python variables

【解决方案1】：

您必须在增加之前设置 numguesses。试试这个：

import random

from datetime import datetime
answer = random.randint(1, 2)
guess = 0
numguesses = 0
now = datetime.now()
play = 'y'


print 'Welcome to Hi-Lo'
print 'The current time is: ' '%s-%s-%s' % (now.year, now.month, now.day)

while play != 'n':
    while guess != answer:
        guess =  int(input('Pick a number inbewteen 1-100 to see if its higher or lower:'))
        if guess == answer:
            numguesses = numguesses + 1
            print 'You are correct! The number was: ' + str(answer)
            print 'It took ' + str(numguesses) + ' guess(es)'
        elif guess > answer:
            print 'Too high'
        else:
            print 'Too low'

    play = str(input('Play again? [y/n]?'))

在将第二个 while 循环嵌套在第一个循环中时，您还犯了另一个缩进错误。我也解决了这个问题。

【讨论】：

【解决方案2】：

你必须给numguesses 一个起始值。试试这个：

numguesses = 0
while guess != answer:
    guess =  int(input('Pick a number inbewteen 1-100 to see if its higher or lower:'))
    if guess == answer:
        numguesses = numguesses + 1

只需在 while 循环之前添加 numguesses = 0 即可。您必须在使用变量之前声明它们。

【讨论】：

【解决方案3】：

  1 #!/usr/bin/env python
  2
  3 import random
  4 from datetime import datetime
  5
  6 answer = random.randint(1, 2)
  7 guess = 0
  8 # You need to define and initialise numguesses before you can increment below by 1
  9 numguesses = 0
 10 now = datetime.now()
 11 play = 'y'
 12
 13 print 'Welcome to Hi-Lo'
 14 print 'The current time is: ' '%s-%s-%s' % (now.year, now.month, now.day)
 15
 16 while play != 'n':
 17   while guess != answer:
 18     guess =  int(input('Pick a number inbewteen 1-100 to see if its higher or lower:'))
 19     if guess == answer:
 20         numguesses = numguesses + 1
 21         print 'You are correct! The number was: ' + str(answer)
 22         print 'It took ' + str(numguesses) + ' guess(es)'
 23         # after the user has guessed correctly, it will start all over again
 24         # hence you need to reset 'guess' and 'numguesses'
 25         guess = 0
 26         numguesses = 0
 27         play = raw_input('Play again? [y/n]? ')
 28         # and you need to get out of the loop altogether if user selects 'n'
 29         break
 30     elif guess > answer:
 31         print 'Too high'
 32         # everytime guess fails, numguesses needs to be increased by 1
 33         numguesses = numguesses + 1
 34     else:
 35         print 'Too low'
 36         # everytime guess fails, numguesses needs to be increased by 1
 37         numguesses = numguesses + 1

请阅读代码中的cmets

【讨论】：