python - 如何在 python 中的文件中的新行上写入输入，而不添加空行？

Question

我想知道，如何让我的代码在文件中的新行上添加每个输入，但不添加额外的空行。目前，我使用“\n”将每个输入写入新行，但这会添加一个额外的空行。有没有办法在不添加额外行的情况下做到这一点？

这是我的所有代码:-

f= open("Passes.py", "a+")
m=open("money.py","r+")
passes= {}
init={}
initial=0
import time
print "Welcome to the virtual banking system"
user=raw_input("Would you like to create a new account? 'Y/N'").lower()
if user== "y":
  new_user= raw_input("Create a username:")
  new_pass= raw_input("Create a password:")
  p= passes[new_user]= new_user + ":" + new_pass
  f.write("\n"+p)
  ask=raw_input("Would you like to sign into your account? 'Y/N'").lower()
  if ask=="y":
    user_in=raw_input("Enter your username:")
    if user_in==new_user:
      pass_in=raw_input("Enter your password:")
      if pass_in==new_pass:
        print "Welcome to your account" + " " + new_user
        useropt=raw_input("Would you like to view your balance- enter 1, deposit money- enter 2, withdraw money- enter 3 or exit- enter 4:")
        if useropt=="1":
          print "Your balance is:", initial
        if useropt=="2":
          amountdep= int(raw_input("How much money would you like to deposit?:"))
          initial+=amountdep
          print "Thanks. Your new balance is:", initial
        if useropt=="3":
          amountwith=int(raw_input("How much would you like to withdraw?:"))
          initial-=amountwith
          print "Your balance is:", initial
        i=init[new_user]=str(initial)
        m.write(str(i)+"\n")
      else:
        print "Password not valid"

    else:
      print "Username does not exist"

  else:
    print "Thanks for using the virtual bank."

else:
  user2=raw_input("Do you have an existing account? 'Y/N'").lower()
  if user2=="y":
    existing_user=raw_input("Enter your username:")
    exisitng_pass=raw_input("Enter your password:")
    for passwords in f:
      if passwords==existing_user+":"+exisitng_pass:
        print "Welcome to your account" + " " + existing_user
        useropt2=raw_input("Would you like to view your balance- enter 1, deposit money- enter 2, withdraw money- enter 3 or exit- enter 4:")
        if useropt2=="1":
          for info in m:
            print "Your balance is:", info
        if useropt2=="2":
          amountdep= int(raw_input("How much money would you like to deposit?:"))
          for info in m:
            a=int(info)+int(amountdep)
            print "Thanks. Your balance is:", int(a)
          m.close()
          m= open("money.py", "w")
          m.write(str(a))
        if useropt2=="3":
          amountwith=int(raw_input("How much would you like to withdraw?:"))
          for info in m:
            t=int(info)-int(amountwith)
            print "Thanks. Your balance is:", t
          m.close()
          m=open("money.py","w")
          m.write(str(t))

Answer 1

要防止尾随换行符，您可以做的就是在字符串的开头打印换行符。这显然会在文件的开头引入一个空行。为了防止这种情况，您可以使用tell()来检查要打印的字符串是否将是文件中的第一行，如果是，则跳过换行符。这应该可以消除尾随换行符的问题。这看起来像这样:

position = m.tell()
if position == 0:
    m.write(str(i))
else:
    m.write('\n'+str(i))