绝对初学者的Python编程

Question

我刚开始学Python，正在通过《绝对初学者的Python编程（第二版 - Python 2.3，但我用的是2.7）》这本书来入门。

书里有一些挑战让我完成，但我在其中一个挑战上遇到了困难；如果有人能帮帮我，我会非常感激，因为我想在继续之前先搞明白这个。

第三章，挑战3 - 猜我的数字：请修改下面的代码，限制玩家猜数字的次数。

我该怎么做呢？到目前为止，我尝试设置一个变量，但无论用户猜对与否，答案总是会被揭晓。提前谢谢大家的帮助。

猜我的数字

电脑随机选择一个1到100之间的数字。玩家尝试去猜这个数字，电脑会告诉玩家猜的数字是太高、太低还是正好。

import random

print "\tWelcome to 'Guess My Number'!"
print "\nI'm thinking of a number between 1 and 100." 
print "Try to guess it in as few attempts as possible.\n"

# set the initial values
the_number = random.randrange(100) + 1
guess = int(raw_input("Take a guess: "))
tries = 1

# guessing loop
while (guess != the_number):
    if (guess > the_number):
        print "Lower..."
    else:
        print "Higher..."

guess = int(raw_input("Take a guess: "))
tries += 1

print "You guessed it!  The number was", the_number
print "And it only took you", tries, "tries!\n"

raw_input("\n\nPress the enter key to exit.")

到目前为止，我尝试了以下方法，但都没有成功。

import random  

print "\tWelcome to 'Guess My Number'!"
print "\nI'm thinking of a number between 1 and 100." 
print "Try to guess it in as few attempts as possible.\n"

# set the initial values
the_number = random.randrange(100) + 1
guess = int(raw_input("Take a guess: "))
tries = 1
limit = 8

# guessing loop
while (guess != the_number and tries < limit):
    if (guess > the_number):
        print "Lower..."
    elif (guess < the_number):
        print "Higher..."
    else:
        print "You've used all " + limit -1 +"of your attempts \
and didn't get the right answer. Shame on You!"

    guess = int(raw_input("Take a guess: "))
    tries += 1

print "You guessed it!  The number was", the_number
print "And it only took you", tries, "tries!\n"

raw_input("\n\nPress the enter key to exit.")

Answer 1

我刚开始学习编程和Python，也在用同一本书。这里是我写的代码，似乎可以正常运行！

# Guess My Number
#
# The computer picks a random number between 1 and 100
# The player tries to guess it and the computer lets
# the player know if the guess is too high, too low
# or right on the money

import random  

print("\tWelcome to 'Guess My Number'!")
print("\nI'm thinking of a number between 1 and 100.")
print("Try to guess it in as few attempts as possible.\n")

# set the initial values
the_number = random.randint(1, 100)
guess = int(input("Take a guess: "))

tries = 1
max_tries = 8

# guessing loop
while tries < max_tries and guess != the_number:

    if guess > the_number:
        print("Lower...")
    elif guess < the_number:
        print("Higher...")

    guess = int(input("Take a guess: "))
    tries += 1

# having it stop if person uses maximum number of tries
if tries >= max_tries:

    print("Ruh roh.  Looks like you're finished, pardner. The number was", the_number)

# text if person gets the right number within the number of tries.
else:
    if guess == the_number:
        print("You guessed it!  The number was", the_number)
        print("And it only took you", tries, "tries!\n")

input("\n\nPress the enter key to exit.")

Answer 2

你这里有一个叫做 tries 的变量。你可以在 while 循环里面检查一下这个变量，如果它达到了某个特定的值，就给用户打印一条消息，然后退出程序；）

Answer 3

我觉得这个练习想教你的是 break 这个语句。在之前，你只有一个退出的条件（就是猜对数字），但现在你还有尝试次数的限制。

有一种简单的方法可以做到这一点：

import random

print "\tWelcome to 'Guess My Number'!"
print "\nI'm thinking of a number between 1 and 100." 
print "Try to guess it in as few attempts as possible.\n"

# set the initial values
the_number = random.randrange(100) + 1

limit = 5
tries = 0

# guessing loop
while True: # we will test the conditions separately in the loop, not here
    # take a guess
    guess = int(raw_input("Take a guess: "))
    tries += 1 

    # first check the number
    if (guess > the_number):
        print "Lower..."
    elif (guess < the_number):
        print "Higher..."
    else: # it can only be equal here
        print "You guessed it!  The number was", the_number
        print "And it only took you", tries, "tries!\n"
        break # exit the while loop

    # now the tries:
    if tries == limit:
        print "You've used all %d of your attempts \
and didn't get the right answer. Shame on You!" % limit
        break

raw_input("\n\nPress the enter key to exit.")