我正在做一项作业。总的来说，我对 Python 和编程还很陌生。
我的任务是创建一个包含 friend 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。我正在努力更改名称。我的问题是，当我更改名称时，它会在每个名称后添加一个新空格。我只想在新名称后添加一个空格。我认为问题出在 replace_line 的定义上。
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
请您参考如下方法:
file.readlines 返回的行已经包含尾随 '\n'，因此您只需添加 '\n'到您要替换的文本:
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，这将确保文件在with block 退出时立即关闭，即使发生异常也是如此。
来自 docs :
It is good practice to use the
withkeyword when dealing with file objects. This has the advantage that the file is properly closed after its suite finishes, even if an exception is raised on the way.
