如何在输入整数而不是字符串时添加错误消息

Question

我试图在输入字符串而不是整数时添加错误。我看过其他类似的帖子，但是当我尝试将其实现到我的代码中时，它不断吐出错误。我这里有一个 1 到 50 之间的猜数字游戏。我一生都无法弄清楚出了什么问题。

import random

number = random.randrange(1, 50)

while True:
    try:
    guess = int ( input("Guess a number between 1 and 50: ") )
    break
except ValueError:
    print("Please input a number.")**
  

while guess != number:
    if guess < number:
        print ("You need to guess higher. Try again.")
        guess = int ( input("\nGuess a number between 1 and 50: ") )
    else:
        print ("You need to guess lower. Try again.")
        guess = int ( input("\nGuess a number between 1 and 50: "))

print ("You guessed the number correctly!")

Answer 1

请注意，您要求三次输入完全相同的输入。实际上没有必要，也根本不需要两个循环。只需将 guess 设置为永远不等于数字的默认值 (None) 并使用一个 input，用 包裹>尝试/除外：

import random

number = random.randrange(1, 50)
guess = None  

while guess != number:
    try:
        guess = int(input("Guess a number between 1 and 50: "))
    except ValueError:
        print("Please input a number.")
    else:
        if guess < number:
            print("You need to guess higher. Try again.")
        elif guess > number:
            print("You need to guess lower. Try again.")

print("You guessed the number correctly!")

Answer 2

您可以尝试为输入语句运行 while 循环。检查输入（字符串格式）是否为数字，然后将其转换为 int。
示例代码：

a = input()
while not a.isnumeric():
    a = input('Enter a valid integer')
a = int(a)

代码一直执行，直到 a 的值为 int

Answer 3

您的代码不起作用，因为缩进不正确

import random

number = random.randrange(1, 50)
while True:
    try:
        guess = int ( input("Guess a number between 1 and 50: ") ) # here
        break # here
    except ValueError: # here
        print("Please input a number.")
  

while guess != number:
    if guess < number:
        print ("You need to guess higher. Try again.")
        guess = int ( input("\nGuess a number between 1 and 50: ") )
    else:
        print ("You need to guess lower. Try again.")
        guess = int ( input("\nGuess a number between 1 and 50: "))

print ("You guessed the number correctly!")

输出

Guess a number between 1 and 50: aa
Please input a number.
Guess a number between 1 and 50: 4
You need to guess higher. Try again.