Python中readlines()读取字符串与输入字符串比对恒为False的问题

你遇到的问题其实很常见——readlines()方法读取文件时，会把每一行末尾的**换行符\n（Windows下是\r\n）**也一并读进字符串里。比如你的songs.txt里第一行是Africa，用readlines()读出来的songname实际是"Africa\n"，而你输入的猜测值是"Africa"，两者看起来一样，但实际是不同的字符串，所以比对永远失败。

修复方案 #

有两种简单的方法可以解决这个问题：

方法1：用strip()去除字符串两端的空白字符 #

在读取每行内容后，调用strip()方法，它会自动去掉字符串开头和结尾的换行符、空格、制表符等空白字符。修改你的代码如下：

import random
from random import randint
loop = 0
score = 0
f = open("songs.txt", "r")
line_number = randint(0,3)
lines = f.readlines()
# 去除换行符及两端空白
songname = lines[line_number].strip()
firstletters = songname.split()
# 修正变量名重复问题，避免覆盖
letters = [word[0] for word in firstletters]
print(" ".join(letters))
f.close()
f = open("artists.txt", "r")
lines = f.readlines()
# 同样处理艺术家名称
artistname = lines[line_number].strip()
print("The first letter of each word in the title of the song is: " + "".join(letters))
print("The artist of the above song is: " + artistname)
print(songname)
answer = songname
guess = input("What is your guess? ")
# 同时转小写，彻底避免大小写匹配问题
if guess.lower() == answer.lower():
    score = score + 3
    print("Correct! You have earned three points, and now have a total of:",score, "points!")
else:
    print("Incorrect! You have one more chance to guess it correctly!")
    guesstwo = input("What is your second guess? ")
    if guesstwo.lower() == answer.lower():
        score = score + 1
        print("Correct! You have earned one point, and now have a total of:",score, "points!")
    else:
        print("Incorrect! Unfortunately you have guessed incorrectly twice- therefore the game has now ended. You had a total of:",score,"points!")

方法2：用splitlines()代替readlines() #

splitlines()方法会自动按换行分割内容，并且不保留换行符，代码修改如下：

# 读取songs.txt时替换readlines()
lines = f.read().splitlines()
songname = lines[line_number]
# 读取artists.txt时同理
lines = f.read().splitlines()
artistname = lines[line_number]

额外提示 #

你原来代码里的letters列表推导式存在变量名重复的问题（firstletters被循环变量覆盖），我已经改成了[word[0] for word in firstletters]，这样代码逻辑更清晰，也避免了潜在的bug。

内容的提问来源于stack exchange，提问作者Ben Hams