Question

我正在完成一项任务。我对Python和编程很新。

我的任务是创建一个包含朋友姓名列表的菜单。然后我应该能够打印名称，添加名称，更改名称和删除名称。我正在改变一个名字。我的问题是，当我更改名称时，它会在每个名称后面添加一个新空格。我只想在新名称后面添加一个空格。我认为问题在于replace_line的定义。

这是我的代码：

from tkinter import*              #imports the Tkinter (GUI) library
master = Tk()                   # Creates a Tk root widget to initialize Tkinter


names_list = Listbox(master)                  # Creates the listbox
names_list.pack()

names_list.insert(0,"Print List of Names")
names_list.insert(1,"Add Name")      #This populates the listbox with the different    options
names_list.insert(2,"Change Name")
names_list.insert(3,"Remove Name")
names_list.insert(4,"Quit")

def replace_line(file_name, line_num, text):         # This creates the function that  will erase names
lines = open(file_name, 'r').readlines()
lines[line_num] = text
out = open(file_name, 'w')
out.writelines('\n'.join(lines))          # Problem Here, adding a new line to every element
out.close()

def CurSelect(evt):                   # defines the CurSelect function that will print out the the value latter selected in the listbox
value=str((names_list.get(names_list.curselection())))

if value =="Print List of Names":           # What to do if  "Print List of Names" is selected
  names = open("C:/Users/Jonathan/Desktop/Classes/GPC/Intro to Comp Sci/Python Name Book Assignment/Names.txt",'r')
  for name in names:         #reads names as a list line by line istead of all on one line
    print(name)
  names.close
else:
    if value == "Add Name":           # What to do if "Add Name" is selected
     names = open("C:/Users/Jonathan/Desktop/Classes/GPC/Intro to Comp Sci/Python Name Book Assignment/Names.txt",'a')
     new_name=input("Type the name you would like to add and press enter")          # This creates a variable that is passes to file.write for appending
     names.write(new_name)
     names.write("\n")                   # This adds a new line after appending the new_name variable
     names.close
    else:
        if value == "Change Name":           # What to do if "Change Name" is selected
            names = open("C:/Users/Jonathan/Desktop/Classes/GPC/Intro to Comp Sci/Python Name Book Assignment/Names.txt",'r')
            phrase = input("Enter name to change")         # Looks for the name to change
            for line in names:           # Looks for the line number that the name to change is on
                if phrase in line:
                   with open("C:/Users/Jonathan/Desktop/Classes/GPC/Intro to Comp Sci/Python Name Book Assignment/Names.txt",'r') as myFile:
                    for num, line in enumerate(myFile, 0):
                        if phrase in line:              # Actually replaces the name with a new name entered by the user
                         phrase_change = input("Enter name to change to")
                         replace_line("C:/Users/Jonathan/Desktop/Classes/GPC/Intro to Comp Sci/Python Name Book Assignment/Names.txt", num, phrase_change)


names_list.bind('<<ListboxSelect>>',CurSelect)       #binds the selection in the listbox to the Curselect function


master.mainloop()                            # Tkinter Event Loop: make the window actually appear

Answer 1

file.readlines返回的行已包含尾随'\n'，因此您只需将'\n'添加到要替换的文本中：

def replace_line(file_name, line_num, text):
    with open(file_name, 'r') as fin, open(file_name, 'w') as out:
        lines = fin.readlines()
        lines[line_num] = text + '\n'             #This should contain a '\n'
        out.writelines(lines)

始终使用with语句来处理文件，它会确保在with块退出后立即关闭文件，即使发生异常也是如此。

来自docs：

在处理文件时，最好使用with关键字对象。这样做的好处是文件在之后正确关闭它的套件即使在路上引发异常也会完成。

如何在替换文件中的行时添加空格

1 个答案: