如何使用新行将内容写入具有多个输入的文本文件？

Question

I have a text file already but it has no content. I want save my inputs in text file and overwrite it instantly if the program reruns. Here is my code

for i in range(0,15):
    ele = input(str(i + 1) + ". ")
    f = open('filename', 'w')
    f.write("%s\n" %(ele))
    f = open('filename', "a")

The only input that is saving is the last one.

For example:

1. A
2. B
3. C
4. D
5. E

..... 15. Z

The only input that is saving is the Z and changed if the user rerun the program

Answer 1

This is happening because you're opening file in 'w' mode also, inside the for loop, which is replacing the contents before append can save you from this.

Do this instead:

for i in range(15):
    mode = 'w' if i==0 else 'a'
    ele = input(str(i + 1) + ". ")
    f = open('filename', mode)
    f.write("%s\n" %(ele))

This program will rewrite the file when program reruns, else it'll append.

According to your comment query, please find the solution below.

S, delimiter = "", " "                      # Set the delimiter value as per your convenience

for i in range(3):
    S += input(str(i + 1) + ". ") + delimiter

f = open('filename', 'w')
f.write(S)

To Reduce Code Size and to Increase Speed, you can use List Comprehension and Chaining

#    Replace " ".join... with delimiter.join...
S = " ".join([input(str(i + 1) + ". ") for i in range(3)]) # List Comprehension
open('filename', 'w').write(S) # Chaining

Answer 2

each time you open the file as w , it will rewrite the whole content, as @Dani Mesejo said, you should open your file before the for loop like this:

f = open('filename', 'w')
for i in range(0,15):
    ele = input(str(i + 1) + ". ")        
    f.write("%s\n" %(ele))
f.close()