如果声明，请避免嵌套？ （Python 2.7）

Question

我从一本名为Invent With Python的书中得到了这个猜谜游戏的想法。我不喜欢原始剧本没有涵盖重新猜测数字或错误地使用不在1 - 20的数字的可能性，所以我修改了它。该程序运行良好，但是，如果/ elif / else代码块，我只是围着我的脑袋。

我想重写脚本而不必嵌套，如果在if中。我甚至无法开始关注如何做到这一点。任何人都可以帮助我 - 只是这个程序如何在没有嵌套的情况下工作的一个例子会很棒！

这是完整的小脚本：

from random import randint
from sys import exit
name = raw_input("Hello! What's your name? ")
print "Well %s, I'm thinking of a number between 1 and 20." % name
print "Since I'm a benevolent computer program, I'll give you 6 guesses."
secret_number = randint(1, 20)

guesses_left = 6
already_guessed = []

while guesses_left > 0:
    try:
        guess = int(raw_input("Take a guess: "))

        if guess >= 1 and guess <= 20 and guess not in already_guessed:
            already_guessed.append(guess)
            guesses_left -= 1

            if guess == secret_number:
                print "You win! %d was my secret number!" % secret_number
                exit(0)
            elif guess < secret_number:
                print "Your guess is too low!"
            elif guess > secret_number:
                print "Your guess is too high!"

        elif guess in already_guessed:
            print "You already guessed that!"

        else:
            print "Not a number between 1 - 20!"
            print "Please try again!"

        print "You have %d guesses left!" % guesses_left

    except ValueError:
        print "Invalid input! Please try again!"    

Answer 1

尝试这样，使用continue退出循环的当前迭代，然后在循环的顶部重新开始。

你这里也有一个逻辑错误：

if guess <= 1 and guess >= 20 and guess not in already_guessed:

数字不可能小于或等于1，大于或等于20.您的and应该是or，如下所示：

if (guess <= 1 or guess >= 20) and guess not in already_guessed:

或更简单：

if 1 <= guess <= 20 and guess not in already_guessed:

另外，只保留try/except可以实际引发异常的事情（或者如果发生异常则不应该发生：

from random import randint
import sys

name = raw_input("Hello! What's your name? ")
print "Well {}, I'm thinking of a number between 1 and 20.".format(name)
print "Since I'm a benevolent computer program, I'll give you 6 guesses."

secret_number = randint(1, 20)
guesses_left = 6
already_guessed = []

while guesses_left > 0:
    print "You have {} guesses left!".format(guesses_left)

    try:
        guess = int(raw_input("Take a guess: "))
    except ValueError:
        print "Invalid input! Please try again!\n"
        continue

    # If the number is not between 1 and 20...
    if not (1 <= guess <= 20):
        print "Not a number between 1 - 20!"
        print "Please try again!\n"
        continue

    if guess in already_guessed:
        print "You already guessed that!\n"
        continue

    guesses_left -= 1
    already_guessed.append(guess)

    if guess == secret_number:
        print "You win! {} was my secret number!".format(secret_number)
        sys.exit(0)
    elif guess < secret_number:
        print "Your guess is too low!\n"
    elif guess > secret_number:
        print "Your guess is too high!\n"

以下是一个示例运行：

Hello! What's your name? :)
Well :), I'm thinking of a number between 1 and 20.
Since I'm a benevolent computer program, I'll give you 6 guesses.
You have 6 guesses left!
Take a guess: 2
Your guess is too low!

You have 5 guesses left!
Take a guess: 2
You already guessed that!

You have 5 guesses left!
Take a guess: 3
Your guess is too low!

You have 4 guesses left!
Take a guess: 7
Your guess is too high!

You have 3 guesses left!
Take a guess: 5
Your guess is too high!

You have 2 guesses left!
Take a guess: 4
You win! 4 was my secret number!

Answer 2

只需将嵌套的if语句更改为elif，如下所示：

from random import randint
from sys import exit
name = raw_input("Hello! What's your name? ")
print "Well %s, I'm thinking of a number between 1 and 20." % name
print "Since I'm a benevolent computer program, I'll give you 6 guesses."
secret_number = randint(1, 20)

guesses_left = 6
already_guessed = []

while guesses_left > 0:
    try:
        guess = int(raw_input("Take a guess: "))

        if guess <= 1 and guess >= 20 and guess not in already_guessed:
            already_guessed.append(guess)
            guesses_left -= 1

        elif guess == secret_number:
            print "You win! %d was my secret number!" % secret_number
            exit(0)
        elif guess < secret_number:
            print "Your guess is too low!"
        elif guess > secret_number:
            print "Your guess is too high!"

        elif guess in already_guessed:
            print "You already guessed that!"

        else:
            print "Not a number between 1 - 20!"
            print "Please try again!"

        print "You have %d guesses left!" % guesses_left

    except ValueError:
        print "Invalid input! Please try again!" 

这是我看到解决你的困境的最简单方法