如何在換行符處從文本文件中拆分文本？

Question

我需要加密一條消息。 該消息如下，它被保存在一個名為assignmenttest.txt的文件中

Hi my name is Allie
I am a Junior
I like to play volleyball

我需要程序來加密每一行並保持其格式，因此，我編寫了以下程序：

fileInputName = input("Enter the file you want to encrypt: ")
key = int(input("Enter your shift key: "))
outputFileName = input("Enter the file name to write to: ")

fileInputOpen = open(fileInputName, "r")
message = fileInputOpen.read()


alphabet = " ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
shiftedStart = alphabet[len(alphabet) - key:]
shiftedEnd = alphabet[:len(alphabet) - key]

shiftedAlphabet = shiftedStart + shiftedEnd

encryptedMessage = ""

for character in message:
    letterIndex = message.split("\n")
    letterIndex = alphabet.find(character)
    encryptedCharacter = shiftedAlphabet[letterIndex]
    #print( "{0} -> {1}".format(character, encryptedCharacter))
    encryptedMessage += encryptedCharacter

print("The encrypted message is: {0}".format(encryptedMessage))


outputFile = open( outputFileName, "w")
print(encryptedMessage, file=outputFile)
outputFile.close()

print("Done writing encrypted message to file {0}".format(outputFileName))

我嘗試在\\ n處使用split，但是輸出未格式化為三行，而是全部為一個長串的加密字母。

關於如何在正確的位置分割加密郵件並使其顯示出來的任何想法？ 我嘗試了多種拆分方法，但均無效果。 非常感謝。

Answer 1

不必在'\\n'處拆分，而是在遇到一個字符時，可以將message中所有非alphabet的字符附加到encryptedMessage message中。

for character in message:
    if !(character in alphabet):
        encryptedMessage += character
        continue  # this takes back to begin of the loop
    letterIndex = alphabet.find(character)
    encryptedCharacter = shiftedAlphabet[letterIndex]
    #print( "{0} -> {1}".format(character, encryptedCharacter))
    encryptedMessage += encryptedCharacter

Answer 2

正如其他答案所說，您可以替換

fileInputOpen = open(fileInputName, "r")
message = fileInputOpen.read()

同

with open(fileInputName, "r") as f:
    messages = f.readlines()

這樣， messages將是一個字符串列表，其中每個字符串都是輸入文件中一行的文本。 然后，對消息中每個字符的循環進行一些細微修改，就可以對messages列表中的每個字符串進行加密。 在這里，我換成你encryptedMessage與currentEncryptedMessage並補充encryptedMessages ，持續跟蹤每個字符串的加密版本列表messages 。

encryptedMessages = []
currentEncryptedMessage = ""

for message in messages:
    for character in message:
        ... # same as code provided
        currentEncryptedMessage += encryptedCharacter
    encryptedMessages.append(currentEncryptedMessage)

寫入文件時，您可以遍歷encryptedMessages每個元素以逐行打印。

with open( outputFileName, "w") as outputFile:
    for message in encryptedMessages:
        print(message, file=outputFile)

因此，您的輸出文本文件將保留輸入文件中的換行符。

Answer 3

而不是一次全部讀取文件。 分別閱讀各行。

f = open("file.txt")
for i in f.readlines():
    print (i)

Answer 4

嘗試更改：

message = fileInputOpen.read()

至

message = fileInputOpen.readlines()

這將使您的文件讀取逐行處理文件。 這將使您可以先逐行進行處理。 除此之外，如果要加密每個字符，則需要另一個for循環用於字符。

Answer 5

1. 您必須循環播放要取消移位的每一行和每個字符；
2. 腳本只能取消轉換字母中出現的alphabet ；
3. 檢查文件是否存在也是必須的，如果文件不存在，則可能會出錯。
4. with open...是在python中讀寫文件的推薦方法。

這是一種方法：

import os
import string

fileInputName = input("Enter the file you want to encrypt: ")
while not os.path.exists(fileInputName):
    fileInputName = input("{} file doesn't exist.\nEnter the file you want to encrypt : ".format(fileInputName))

key = int(input("Enter your shift key (> 0): "))
while key < 1 :
    key = int(input("Invalid shift key value ({}) \nEnter your shift key (> 0): ".format(key)))

fileOutputName = input("Enter the file name to write to: ")
if os.path.exists(fileOutputName) :
    ow = input("{} exists, overwrite? (y/n): ".format(fileOutputName))
    if not ow.startswith("y"):
        fileOutputName = input("Enter the file name to write to: ") # asks for output filename again

alphabet = string.ascii_letters + " "
shiftedStart = alphabet[len(alphabet) - key:]
shiftedEnd = alphabet[:len(alphabet) - key]
shiftedAlphabet = shiftedStart + shiftedEnd

with open(fileOutputName, "a") as outputFile: # opens out file
    with open(fileInputName, "r") as inFile:  # opens in file
        for line in inFile.readlines(): # loop all lines in fileInput
            encryptedCharacter = ""
            for character in line: # loop all characters in line
                if character in alphabet: # un-shift only if character is present in `alphabet`
                    letterIndex = alphabet.find(character)
                    encryptedCharacter += shiftedAlphabet[letterIndex]
                else:
                    encryptedCharacter += character # add the original character un-shifted
            outputFile.write("{}".format(encryptedCharacter)) # append line to outfile