python - 如何使用循环检查输入是否已存在于 Python 文件中并追加(如果是新的)？

Question

我想使用循环来检查输入是否已存在于文件中，无论它是否在列表/字典中。虽然我设法将输入记录在 .txt 文件中，但如何检查重复性以便只 append 新输入？

f = open('History.txt', 'a+')

while True:
    new_word = (input('Please enter an English word:'))
    if new_word.isalpha() == True:
        break
    else:
        print ('You''ve entered an invalid response, please try again.')
        continue

f.seek(0)
f.read()
if new_word in f:
    print ('The word has been recorded previously. You may proceed to the next step.')
else:
    f.write(new_word + '\n')

f.close()

目前，.txt 文件只是不断记录输入，而不管重复性。

Answer 1

首先，我强烈建议使用 Contextmanager用于打开文件。这将确保文件已关闭。

with open(path, "a+") as f:
    content = f.read
    # DO more stuff

然后在您的代码中检查 new_word 是否在 f 中。但f实际上是一个文件对象，而不是str。相反，请执行以下操作:

if new_word in f.read():

f.read() 返回一个字符串

可能的最终代码

with open('History.txt', 'a+') as f:
  while True:
    new_word = (input('Please enter an English word:'))
    if new_word == "SOME KEYWORD FOR BREAKING":
      break
    else:
      file_position = f.tell() # To Keep appending
      f.seek(0) # read from start
      file_content = f.read()       
      f.seek(file_position) # write to end
      if new_word in file_content:
        print ('The word has been recorded previously. You may proceed to the next step.')
      else:
        f.write(new_word + '\n')