Is there a way to taker user input as a txt file and then rewrite it into a new txt file?

I am writing a program where the user inputs their txt file. The txt file is read and then the txt file is written into a new txt file. The new txt file has one word on each line. I am able to write the program without the user input and it works perfectly. Once I add the user input it tells me the txt file does not exist in my directory (even though it does). Am I not sure what I am doing wrong. Please point me in the direction of easy tutorials I can watch to solve this problem.

This is the code that doesn't work

outputString = " "

userinput = input('Enter the name of the file you want to read:' + " ")

myfile = open(userinput, 'r')

myOutputFile = open(userinput_Output, 'a')


for line in myfile:
    words = line.split()

    for current in words:
        myOutputFile.write(current + "\n")
        
myfile.close()

myOutputFile.close()

This is the code that works (you can test it out with your own txt files and see that it does actually work if you don't want to take my word for it.)

outputString = " "

myfile = open("readme.txt", 'r')

myOutputFile = open("readme_Output.txt", 'a')


for line in myfile:
    words = line.split()

    for current in words:
        myOutputFile.write(current + "\n")
        
myfile.close()

myOutputFile.close()

The reason why is because userinput_Output is not defined.

What you need to do is concatenate userinput to _Output.txt.

I have flagged where the correction would go in the code below.

userinput = input('Enter the name of the file you want to read: ')

# open the files
path = 'C:/path/to/folder/with/files/'
myfile = open(path + userinput+'.txt', 'r')
myOutputFile = open(path + userinput+"_output.txt", 'a')   # <---  this line


for line in myfile:
    words = line.split()

    for current in words:
        myOutputFile.write(current + "\n")
        
# close the files
myfile.close()
myOutputFile.close()

Here are the data results.

example input text file (test.txt):

hello world
hello moon

resulting output text file (test_output.txt):

hello
world
hello
moon

As an extra, you can open both files in a context manager (which handles closing both automatically, like this) which is much cleaner:

userinput = input('Enter the name of the file you want to read: ')

path = 'C:/path/to/folder/with/files/'
input_file = os.path.join(path, userinput + '.txt')
output_file = os.path.join(path, userinput + '_output.txt')

with open(input_file, 'r') as myfile, open(output_file, 'a') as myOutputFile:
    for line in myfile:
        words = line.split()
        for current in words:
            myOutputFile.write(current + "\n")