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How do I make sure that the program asks the user for input again, when the user enters a file that already exists or doesnt exist? depending on the function that the user has called like for example if the user wants to delete a file if he enters a file name that doesnt exist the program prompts an error and ask for the input again instead of showing "
FileNotFoundError: [WinError 2] The system cannot find the file specified
FileNotFoundError: [WinError 2] The system cannot find the file specified
, also i want the code to be short so that i have to make small adjustments
Here's is the code
<pre>def read(filename):
    while True:
        try:
            filename = str(input("Enter the file name: "))
            with open(filename, 'r') as f:
                for content in f.readlines():
                    print(content)
            break
        except FileNotFoundError:
            print("Doesn't exist! ")
            continue


####### read function ##########
def first_n_lines_from_a_file(filename, line_to_read):  #### to read from last just put -line_to_read
    with open(filename, 'r') as f:
        for line in (f.readlines()[line_to_read:]):
            print(line, end="")


######## First n lines ############
def append_to_file(filename, write_to_file):
    with open(filename, 'a') as f:
        f.write(write_to_file)


######## Append ########
def string_to_search_and_line_number(filename, string_to_search):
    line_number = 0
    list_of_results = []
    # Open the file in read only mode
    with open(filename, 'r') as read_obj:
        # Read all lines in the file one by one
        for line in read_obj:
            # For each line, check if line contains the string
            line_number += 1
            if string_to_search in line:
                # If yes, then add the line number & line as a tuple in the list
                list_of_results.append((line_number, line.rstrip()))
        # Return list of tuples containing line numbers and lines where string is found
    print(list_of_results)


def del_file(filename):
    import os
    os.remove(filename)


def new_file(filename):
    with open(filename, "x") as file:
        pass


def replace_text(filename, text_to_search):
    import fileinput
    import os
    import sys
    with open(filename, 'r+') as file:
        text_to_replace = str(input("Enter the word to replace with: "))
        count = 0
        for line in fileinput.input(filename):
            if text_to_search in line:
                count += 1
                print("Match found!", "\n", "Line Number: ", count)
            elif text_to_search not in line:
                print("Match not found!")
                count += 1
            file.write(line.replace(text_to_search, text_to_replace))


################### main program #############################
print("Type 0 to quit!", "\n", "Type 1 to read the file", "\n", "Type 2 to read first n lines of a file", "\n",
      "Type 3 to append to the file", "\n", "Type 4 to Search a string along with the line number in the file", "\n",
      "Type 5 to create a new file", "\n", "Type 6 to delete a file", "\n",
      "Type 7 to replace text in a file")  ### menu prompt ####
while True:  ## to re-run the program based on user input ###
    while True:
        try:
            user_input = int(input("Input: "))
            break
        except:
            print("invalid response! ")
    while user_input > 7 or user_input < 0:  #### so that it is in range ####
        print("Invalid response!")
        user_input = int(input("Input: "))
    if user_input == 1:
        read("")
    elif user_input == 2:
        filename = input("Enter the file name: ")
        line_to_read = int(input("Enter the line to read: "))
        first_n_lines_from_a_file(filename, line_to_read)
    elif user_input == 3:
        filename = input("Enter the file name: ")
        write_to_file = str(input("Enter the word you want to append: "))
        append_to_file(filename, write_to_file)
    elif user_input == 4:
        filename = input("Enter the file name: ")
        string_to_search = str(input("Enter the string you want to search: "))
        string_to_search_and_line_number(filename, string_to_search)
    elif user_input == 6:
        filename = input("Enter the file name: ")
        del_file(filename)
    elif user_input == 5:
        filename = input("Enter the file name: ")
        new_file(filename)
    elif user_input == 7:
        filename = input("Enter the file name: ")
        text_to_search = input("Enter the word you want to search: ")
        replace_text(filename, text_to_search)
    elif user_input == 0:
        print("Quiting....")
        quit()
    ##### to re--run the program ######
    while True:
        answer = str(input('Run again? (y/n): '))
        if answer in ('y', 'n'):
            break
        else:
            print("invalid input! ")
    if answer == 'y':
        continue
    else:
        print("Goodbye")
        break

This is the Output when i enter a file name that doesnt exist
---------OUPTPUT---------------------
Type 0 to quit! 
 Type 1 to read the file 
 Type 2 to read first n lines of a file 
 Type 3 to append to the file 
 Type 4 to Search a string along with the line number in the file 
 Type 5 to create a new file 
 Type 6 to delete a file 
 Type 7 to replace text in a file
Input: 6
Enter the file name: wwe
Traceback (most recent call last):
FileNotFoundError: [WinError 2] The system cannot find the file specified: 'wwe'


What I have tried:

I have tried try/except by putting the File Not found error but it for some reason is not doing what it's suppose
Posted
Updated 9-Jul-22 6:23am

1 solution

Look at your code:
Python
elif user_input == 6:
    filename = input("Enter the file name: ")
    del_file(filename)

But the del_file code is not inside a try/catch block so if the file does not exist you get a system exception. You should create a function that gets the filename and checks if it exists first. You should also add a count so the user does not spend the rest of their life typing invalid names.
 
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