是否可以在 while 循环中更改变量的值？
Is it possible to change a variable’s value while it is in the `while` loop?
我正在尝试编写代码来解决一个问题：
Generate a random number between 1 and 9 (including 1 and 9). Ask the user to guess the number, then tell them whether they guessed too low, too high, or exactly right. Keep track of how many guesses the user has taken, and when the game ends, print this out.
我写的代码是：
import sys
import random
x=random.randint(1,9)
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
for i in range (10):
z=input()
if int(z)<x:
print('Too low. Please try again.')
elif int(z)>x:
print('Too high. Please try again.')
elif int(z)==x:
print('You guessed it right!')
if i==0:
print('It took you a single turn! Nice')
else:
print('it took you ' + str(i+1)+' turns.')
print('Do you want to play again? Yes or No?')
j=input()
if j.lower()=='yes':
print('Okay, Please enter a number between 1 and 9 including the extremes.')
pass
else:
sys.exit()
这是 运行 时的样子：
Hello there! Please enter a number between 1 and 9 including the extremes.
4
Too high. Please try again.
3
Too high. Please try again.
2
You guessed it right!
it took you 3 turns.
Do you want to play again? Yes or No?
yes
Okay, Please enter a number between 1 and 9 including the extremes.
6
Too high. Please try again.
4
Too high. Please try again.
2
You guessed it right!
it took you 6 turns.
Do you want to play again? Yes or No?
看，当 for 循环首次执行时，代码给出了完美的结果。当我们第二次尝试 运行 这个“游戏”时，当它问我们这个问题时说 yes，它会给出奇怪的结果：Do you want to play again? Yes or No?。
是否可以在 python 到达倒数第 4 行时放置 i=0 并且 for 循环从 i=0 再次开始，这样我就不会得到奇怪的结果？
或者是否有其他更简单的方法来消除此错误？
您的全部代码都嵌入到 for 循环中，并且永远不会重置计数器。如果你想在 for 循环中重置 i，你必须在 for 循环之外定义它，以便它具有全局范围。
您可以对任务使用 while 循环。并且您应该添加异常处理方法来获取输入。
import random
cond = True
while cond:
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
x=random.randint(1,9)
for i in range (10):
z=int(input())
if int(z)<x:
print('Too low. Please try again.')
elif int(z)>x:
print('Too high. Please try again.')
elif int(z)==x:
print('You guessed it right!')
import sys
if i==0:
print('It took you a single turn! Nice')
else:
print('it took you ' + str(i+1)+' turns.')
print('Do you want to play again? Yes or No?')
j=input()
if j.lower()=='yes':
break
else:
cond = False
sys.exit()
首先，你只选择了一次随机数，所以它总是相同的。
其次，你的游戏应该是 while 循环而不是 for 循环（如果你想让玩家在猜完后重新开始）。
turns = 0
while True:
secret_number = random.randint(1,9)
print('Please enter a number between 1 and 9 including the extremes.')
guess = input()
turns += 1
if int(guess) < secret_number:
print("Too low")
elif int(guess) > secret_number:
print("Too high")
else:
print("You guessed in {} turn(s)".format(turns))
你继续循环，如果用户想继续玩，则分配 turns = 0，如果他不想继续玩，你就中断。
我可能会这样写。
from itertools import count
from random import randint
def run_game():
random_value = randint(1, 9)
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
for i in count():
guess_string = input()
try:
guess = int(guess_string)
except ValueError:
print("Invalid value given for guess: {}".format(guess_string))
if guess < random_value:
print("Too low! Please try again.")
elif guess > random_value:
print("Too high! Please try again.")
else:
print('You guessed it right!')
if not i:
print('It took you a single turn! Nice')
else:
print('it took you {} turns.'.format(i + 1))
print('Do you want to play again? Yes or No?')
response_string = input()
return response_string.lower() == 'yes'
if __name__ == "__main__":
while run_game():
pass
但是，为了便于理解：
from itertools import count
from random import randint
if __name__ == "__main__":
playing = True
while playing:
random_value = randint(1, 9)
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
for i in count():
guess_string = input()
try:
guess = int(guess_string)
except ValueError:
print("Invalid value given for guess: {}".format(guess_string))
if guess < random_value:
print("Too low! Please try again.")
elif guess > random_value:
print("Too high! Please try again.")
else:
print('You guessed it right!')
if not i:
print('It took you a single turn! Nice')
else:
print('it took you {} turns.'.format(i + 1))
print('Do you want to play again? Yes or No?')
response_string = input()
if response_string.lower() != 'yes':
playing = False
break
所有导入都应该放在文件的顶部。然后，放置一个 while 循环，以便玩家可以在每场比赛后重新开始；这样，变量 x 也会在每场比赛后重置。此外，第一次打印应该放在 while 和 for 循环之外，因此它只打印一次（最后一次 if 将在新游戏开始时打印新提示）。
此时您的代码应如下所示：
import random
import sys
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
while True:
x=random.randint(1,9)
for i in range (10):
z=input()
if int(z)<x:
print('Too low. Please try again.')
elif int(z)>x:
print('Too high. Please try again.')
elif int(z)==x:
print('You guessed it right!')
if i==0:
print('It took you a single turn! Nice')
else:
print('it took you ' + str(i+1)+' turns.')
print('Do you want to play again? Yes or No?')
j=input()
if j.lower()=='yes':
print('Okay, Please enter a number between 1 and 9 including the extremes.')
else:
sys.exit()
我正在尝试编写代码来解决一个问题：
Generate a random number between 1 and 9 (including 1 and 9). Ask the user to guess the number, then tell them whether they guessed too low, too high, or exactly right. Keep track of how many guesses the user has taken, and when the game ends, print this out.
我写的代码是：
import sys
import random
x=random.randint(1,9)
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
for i in range (10):
z=input()
if int(z)<x:
print('Too low. Please try again.')
elif int(z)>x:
print('Too high. Please try again.')
elif int(z)==x:
print('You guessed it right!')
if i==0:
print('It took you a single turn! Nice')
else:
print('it took you ' + str(i+1)+' turns.')
print('Do you want to play again? Yes or No?')
j=input()
if j.lower()=='yes':
print('Okay, Please enter a number between 1 and 9 including the extremes.')
pass
else:
sys.exit()
这是 运行 时的样子：
Hello there! Please enter a number between 1 and 9 including the extremes.
4
Too high. Please try again.
3
Too high. Please try again.
2
You guessed it right!
it took you 3 turns.
Do you want to play again? Yes or No?
yes
Okay, Please enter a number between 1 and 9 including the extremes.
6
Too high. Please try again.
4
Too high. Please try again.
2
You guessed it right!
it took you 6 turns.
Do you want to play again? Yes or No?
看，当 for 循环首次执行时，代码给出了完美的结果。当我们第二次尝试 运行 这个“游戏”时，当它问我们这个问题时说 yes，它会给出奇怪的结果：Do you want to play again? Yes or No?。
是否可以在 python 到达倒数第 4 行时放置 i=0 并且 for 循环从 i=0 再次开始，这样我就不会得到奇怪的结果？
或者是否有其他更简单的方法来消除此错误？
您的全部代码都嵌入到 for 循环中，并且永远不会重置计数器。如果你想在 for 循环中重置 i，你必须在 for 循环之外定义它，以便它具有全局范围。
您可以对任务使用 while 循环。并且您应该添加异常处理方法来获取输入。
import random
cond = True
while cond:
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
x=random.randint(1,9)
for i in range (10):
z=int(input())
if int(z)<x:
print('Too low. Please try again.')
elif int(z)>x:
print('Too high. Please try again.')
elif int(z)==x:
print('You guessed it right!')
import sys
if i==0:
print('It took you a single turn! Nice')
else:
print('it took you ' + str(i+1)+' turns.')
print('Do you want to play again? Yes or No?')
j=input()
if j.lower()=='yes':
break
else:
cond = False
sys.exit()
首先，你只选择了一次随机数，所以它总是相同的。
其次，你的游戏应该是 while 循环而不是 for 循环（如果你想让玩家在猜完后重新开始）。
turns = 0
while True:
secret_number = random.randint(1,9)
print('Please enter a number between 1 and 9 including the extremes.')
guess = input()
turns += 1
if int(guess) < secret_number:
print("Too low")
elif int(guess) > secret_number:
print("Too high")
else:
print("You guessed in {} turn(s)".format(turns))
你继续循环，如果用户想继续玩，则分配 turns = 0，如果他不想继续玩，你就中断。
我可能会这样写。
from itertools import count
from random import randint
def run_game():
random_value = randint(1, 9)
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
for i in count():
guess_string = input()
try:
guess = int(guess_string)
except ValueError:
print("Invalid value given for guess: {}".format(guess_string))
if guess < random_value:
print("Too low! Please try again.")
elif guess > random_value:
print("Too high! Please try again.")
else:
print('You guessed it right!')
if not i:
print('It took you a single turn! Nice')
else:
print('it took you {} turns.'.format(i + 1))
print('Do you want to play again? Yes or No?')
response_string = input()
return response_string.lower() == 'yes'
if __name__ == "__main__":
while run_game():
pass
但是，为了便于理解：
from itertools import count
from random import randint
if __name__ == "__main__":
playing = True
while playing:
random_value = randint(1, 9)
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
for i in count():
guess_string = input()
try:
guess = int(guess_string)
except ValueError:
print("Invalid value given for guess: {}".format(guess_string))
if guess < random_value:
print("Too low! Please try again.")
elif guess > random_value:
print("Too high! Please try again.")
else:
print('You guessed it right!')
if not i:
print('It took you a single turn! Nice')
else:
print('it took you {} turns.'.format(i + 1))
print('Do you want to play again? Yes or No?')
response_string = input()
if response_string.lower() != 'yes':
playing = False
break
所有导入都应该放在文件的顶部。然后，放置一个 while 循环，以便玩家可以在每场比赛后重新开始；这样，变量 x 也会在每场比赛后重置。此外，第一次打印应该放在 while 和 for 循环之外，因此它只打印一次（最后一次 if 将在新游戏开始时打印新提示）。
此时您的代码应如下所示：
import random
import sys
print('Hello there! Please enter a number between 1 and 9 including the extremes.')
while True:
x=random.randint(1,9)
for i in range (10):
z=input()
if int(z)<x:
print('Too low. Please try again.')
elif int(z)>x:
print('Too high. Please try again.')
elif int(z)==x:
print('You guessed it right!')
if i==0:
print('It took you a single turn! Nice')
else:
print('it took you ' + str(i+1)+' turns.')
print('Do you want to play again? Yes or No?')
j=input()
if j.lower()=='yes':
print('Okay, Please enter a number between 1 and 9 including the extremes.')
else:
sys.exit()