在 Python 中，如果输入有效，如何使条件 if 循环不执行？答案

【问题标题】：In Python, How do I make my conditional if loop not execute if input is valid?在 Python 中，如果输入有效，如何使条件 if 循环不执行？
【发布时间】：2016-10-31 13:20:42
【问题描述】：

#Write a short program that will do the following
#Set a value your favorite number between 0 and 100
#Ask the user to guess your favorite number between 0 and 100
#Repeat until they guess that number and tell them how many tries it took
#If the value they guessed is not between 0 and 100
#tell the user invalid guess and do not count that as an attempt

我的问题是，即使用户猜到了 0 到 100 之间的数字，它仍然会打印出“猜错。再试一次”。如果输入可接受（1-100），我如何控制我的循环跳过打印语句和问题重复？提前致谢！

favoriteNumber = 7
attempts = 0

guess = raw_input("Guess a number between 0 and 100: ")

if (guess  < 0) or (guess > 100):
    print "Invalid guess. Try again"
    guess = raw_input("Guess a number between 0 and 100: ")

attempts1 = str(attempts)
print "it took " + attempts1 + "attempts."

【问题讨论】：

什么循环？您的代码中没有任何循环。

标签： python validation loops input

【解决方案1】：

使用输入而不是raw_input，所以你得到的是整数而不是字符串

favoriteNumber = 7
attempts = 0


while True:
    guess = input("Guess a number between 0 and 100: ")
    if (guess  < 0) or (guess > 100):

        attempts=attempts+1
        print "Invalid guess. Try again"
    else:
        attempts=attempts+1
        break

attempts1 = str(attempts)
print "it took " + attempts1 + " attempts."

【讨论】：

非常感谢大家，但您对我的帮助最大。

【解决方案2】：

您的 raw_input 返回一个字符串，该字符串始终为 > 100。将其转换为带有 int(raw_input()) 的数字

【讨论】：

【解决方案3】：

在 Python 2.7.10 中，如果您不将字符串转换为整数，它似乎会接受它，但适用于数字的所有规则都返回 false。这是一个工作示例：

favoriteNumber = 7
attempts = 0

guess = raw_input("Guess a number between 0 and 100: ")

if (int(guess)  < 0) or (int(guess) > 100):
    print "Invalid guess. Try again"
    guess = raw_input("Guess a number between 0 and 100: ")

attempts1 = str(attempts)
print "it took " + attempts1 + " attempts."

在 Python 3.4 中，原始代码会产生一个错误，告诉您它是字符串而不是整数。但是，就像 Paul 所说，您可以将 raw_input 放在 int() 命令中。

【讨论】：