运行此代码时，为什么循环不等待我的响应？答案

【问题标题】：When running this code, why does the loop not wait for my response?运行此代码时，为什么循环不等待我的响应？
【发布时间】：2019-12-26 01:47:44
【问题描述】：

import random

def rock_paper_scissors(choice):
    computer_choice = random.choice(['rock', 'paper', 'scissors'])
    while True:
        if choice == computer_choice:
            print("Tie! Play again.")
            choice
        elif choice.lower() == 'quit':
            break

        elif choice.lower() == 'rock' and computer_choice.lower() == 'paper':
            print("TRY AGAIN!", computer_choice.lower(), "beats", choice.lower())
            choice
        elif choice.lower() == 'rock' and computer_choice.lower() == 'scissors':
            print("YOU WON!", choice.lower(), "beats", computer_choice.lower())
            choice
        elif choice.lower() == 'paper' and computer_choice.lower() == 'scissors':
            print("TRY AGAIN!", computer_choice.lower(), "beats", choice.lower())
            choice
        elif choice.lower() == 'paper' and computer_choice.lower() == 'rock':
            print("YOU WON!",  choice.lower(), "beats", computer_choice.lower())
            choice
        elif choice.lower() == 'scissors' and computer_choice.lower() == "rock":
            print("TRY AGAIN!", computer_choice.lower(), "beats", choice.lower())
            choice
        elif choice.lower() == 'scissors' and computer_choice.lower() == "paper":
            print("YOU WON!", choice.lower(), 'beats', computer_choice.lower())
            choice
        else:
            print("Sorry, invalid.")
            choice

print(rock_paper_scissors(input("Rock paper or scissors (enter 'q' to quit): ")))

运行此代码时，elif 中打印的任何内容都会在运行框中一遍又一遍地重复。我不知道是否应该修复 while 语句或在 elif 语句中添加其他代码。输入工作正常，但我不知道在 while 循环中添加什么。（我是一个初学 Python 程序员）

【问题讨论】：

while True: 根据定义会一遍又一遍地重复，除非你有办法跳出循环。我想你只是想删除while 声明。
您必须请求用户输入，而不是输入choice 语句（没有效果）。提示：在所有ifs 检查后，您只能请求用户输入一次
@dcg 你为什么写在评论里？这正是答案......即使是stackoverflow也不愿意在评论中给出答案，并且仅将其用于添加信息。

标签： python while-loop infinite

【解决方案1】：

输入语句不在while循环的范围内，所以只调用一次。

一旦进入 while 循环，选择变量不会发生任何变化，因此会一遍又一遍地触发相同的打印语句。

将输入语句与计算机选择初始化一起移动到 while 循环中（这样计算机每次都可以选择一个新选项）可以解决您的问题。

import random
def rock_paper_scissors():  
    while True:
        computer_choice = random.choice(['rock', 'paper', 'scissors'])
        choice = input("Rock paper or scissors (enter 'q' to quit): ")
        if choice == computer_choice:
            print("Tie! Play again.")
        elif choice.lower() == 'quit':
            break
        elif choice.lower() == 'rock' and computer_choice.lower() == 'paper':
            print("TRY AGAIN!", computer_choice.lower(), "beats", choice.lower())
        elif choice.lower() == 'rock' and computer_choice.lower() == 'scissors':
            print("YOU WON!", choice.lower(), "beats", computer_choice.lower())
        elif choice.lower() == 'paper' and computer_choice.lower() == 'scissors':
            print("TRY AGAIN!", computer_choice.lower(), "beats", choice.lower())
        elif choice.lower() == 'paper' and computer_choice.lower() == 'rock':
            print("YOU WON!",  choice.lower(), "beats", computer_choice.lower())
        elif choice.lower() == 'scissors' and computer_choice.lower() == "rock":
            print("TRY AGAIN!", computer_choice.lower(), "beats", choice.lower())
        elif choice.lower() == 'scissors' and computer_choice.lower() == "paper":
            print("YOU WON!", choice.lower(), 'beats', computer_choice.lower())
        else:
            print("Sorry, invalid.")
rock_paper_scissors()

【讨论】：

【解决方案2】：

我想我会分享另一种写这篇文章的方法，这可能对初学者有帮助。目标是：

为了减少重复，所以您只有一个print("You Lose")，而不是三个。
将获胜的逻辑分离到一个单独的函数中，这样更容易测试逻辑部分并允许代码重用。

import random

def did_player_win(computer, player):
    # Returns None for a tie, True for a win, False for a lose

    if computer == player:
        return None

    if computer == 'paper':
        return False if player == 'rock' else True

    if computer == 'scissors':
        return False if player == 'paper' else True

    if computer == 'rock':
        return False if player == 'scissors' else True


def play():
    while True:
        player = input("Rock, paper or scissors (enter 'q' to quit): ")
        player = player.lower()
        if player not in ['rock', 'paper', 'scissors']:
            break

        computer = random.choice(['rock', 'paper', 'scissors'])

        player_won = did_player_win(computer, player)
        if player_won is True:
            print("YOU WON! {0} beats {1}".format(player, computer))    
        elif player_won is False:
            print("TRY AGAIN! {0} beats {1}".format(computer, player))
        else:
            print("Tie!  Both chose {0}".format(player))

play()

【讨论】：