Python读取文件和删除项目

Question

The question is write a program that will ask the user for a fruit they dislike. Next, read the groceries.txt file and create a new file called groceries.new with the fruit that the user dislikes removed.

what i written so far is... I don't know how to delete the item from the file.

groceries = open('groceries.txt', 'r')

groceries_contents = groceries.read()

groceries_new = open('groceries.new.txt', 'w')

groceries_new.write(groceries_contents)

groceries_new_contents = groceries_new.read()

fruit = raw_input ("What fruit do you dislike? ")
if fruit in groceries_new_contents:
     del fruit 


groceries.close()
groceries_new.close()

Answer 1

The trick here is you are not really "delete" the item. After you have read the content, you check whether it is the fruit the user dislikes. If yes, then you do not write to the new file; if not, then you write to the new file. Hope it helps.

Answer 2

fruit = raw_input("What fruit do you dislike? ")
with open("groceries.txt") as file, open("groceries.new", "w") as output_file:
    for line in file:
        if fruit not in line: 
            output_file.write(line) # save line if it doesn't contain the fruit