Python中的剪刀石头布函数帮助

Question

我刚开始学习Python，正在为我的作业写一个简单的石头剪刀布程序。这个游戏计划进行10轮，并记录玩家和电脑之间的得分。不过，我遇到了两个具体的问题。

import random

def welcome_prompt():
    print ("ROCKER PAPER SCISSORS in PYTHON Assignment")        
    print ("Rules: Rocks beats Scissors, Scissors beats Paper, Paper beats Rock")

def get_player_move():
    print ('Round ' + str(round))        
    print ("Please play one of the following")
    get_player_move = raw_input(" 1) [R]ock, 2) [P]aper, 3) [S]cissors:")

    if get_player_move == ("R"):
        print ("You used Rock!") 
        return 1              

    elif get_player_move == ("P"):        
        print ("You used Paper!")
        return 2

    elif get_player_move == ("S"):
        print ("You used Scissors!")
        return 3

    else:
        print "Invalid input, please use capitalized initial (R,P,S)"
        return get_player_move()

def get_computer_move():
        get_computer_move = random.randint(1,3)

        if get_computer_move == 1:
            print ("Computer used Rock!")
        return 1

    elif get_computer_move == 2:
        print ("Computer used Paper!")
        return 2

    elif get_computer_move == 3:
        print ("Computer used Scissors!")
        return 3



def compare_moves(get_player_move, get_computer_move):
# Rock = 1
# Paper = 2
# Scissors = 3

    if (get_player_move ==  1 and get_computer_move == 1) or (get_player_move == 2 and get_computer_move == 2) or (get_player_move == 3 and get_computer_move == 3):
    print ("It's a tie!")
    return 0  

    elif (get_player_move == 1 and get_computer_move == 3) or (get_player_move == 2 and get_computer_move == 1) or (get_player_move == 3 and get_computer_move == 2):
    print ("You win the round!")
    return 1

    elif (get_player_move == 1 and get_computer_move == 2) or (get_player_move == 2 and get_computer_move == 3) or (get_player_move == 3 and get_computer_move == 1):
    print ("You lose the round!")
    return -1

    elif (get_player_move == 4):
    print ("You didn't put in correct input, computer gets a free win")
    return -1


# Game Program

player_score = 0
comp_score = 0
round = 0


welcome_prompt()

('Round ' + str(round))
while round< 10:
    round = round + 1
    get_player_move()
    get_computer_move()
    compare_moves(get_player_move, get_computer_move)

    if compare_moves == 1:
        player_score = player_score + 1
        print 'Player Score'+ str(player_score)
        print 'Computer Score'+ str(player_score)
    elif compare_moves == -1:
        comp_score = comp_score + 1
        print 'Player Score'+ str(player_score)
        print 'Computer Score'+ str(player_score)        

print "Game Over"

首先，我无法让compare_move函数正确获取get_player_move和get_computer_move返回的值。虽然游戏可以运行而没有错误，但它完全跳过了比较和得分的部分。我对基础知识还有点不太熟悉，所以不太确定缺少了什么。

其次，在get_player_move函数中，当我输入一个无效的内容（比如：blah）来测试raw_input时，它会报错。

Traceback (most recent call last):
  File "C:\Python27\Rock Paper Scissors.py", line 85, in <module>
    get_player_move()
  File "C:\Python27\Rock Paper Scissors.py", line 32, in get_player_move
    return get_player_move()
TypeError: 'str' object is not callable

那么，如何让一个函数在输入无效内容后，能够再次请求正确的raw_input，而不打断while循环呢？

非常感谢你的解释！

Answer 1

你在函数 get_player_move() 里面有一个局部变量 get_player_move；所以你不能再用这个函数的名字（全局的）了。

你需要给这个局部变量换个名字。

所以，不要这样：

get_player_move = raw_input(" 1) [R]ock, 2) [P]aper, 3) [S]cissors:")

要这样：

move = raw_input(" 1) [R]ock, 2) [P]aper, 3) [S]cissors:")

可能是这样的。

获取用户输入时，最好不要依赖递归。因为用户可能一直按 'C'，这样你的程序就会因为 RuntimeError: maximum recursion depth exceeded 而崩溃。用循环会更简单：

while True:
    move = raw_input(" 1) [R]ock, 2) [P]aper, 3) [S]cissors:")
    if move == "R":
        print ("You used Rock!") 
        return 1              

    # etc.

    else:
        print "Invalid input, please use capitalized initial (R,P,S)"

当你在函数里做出正确选择时，会返回并自动退出循环。如果到最后打印出 Invalid input，那么 while True 循环会重新从头开始，用户会再次被要求输入选择。

接下来：虽然你的函数返回了一个选择（一个整数），但你从来没有保存这个返回值。你必须在调用函数的地方保存它：

player_move = get_player_move()
computer_move = get_computer_move()
result = compare_moves(player_move, computer_move)

if result == 1:

注意，保存返回值的不是函数名，而是一个单独的变量。例如，player_move 被赋值为 get_player_move() 返回的内容。

然后你可以把这些返回的值传给 compare_moves()；它也会返回一个结果，这里存储在 result 里以便后续比较。