Question

Write a program that loops, prompting the user for their full name, their exam result (an integer between 1 and 100), and then writes that data out to file called ‘customers.txt’. The program should check inputs for validity according to the following rules:

• First and last names must use only alphabetical characters. No spaces, hyphens or special characters. Names must be less than 20 characters long.
• Exam result (an integer between 1 and 100 inclusive)

The file should record each customers information on a single line and the output file should have the following appearance.

Nurke Fred 58

Cranium Richard 97

Write a second program that opens the ‘customers.txt’ file for reading and then reads each record, splitting it into its component fields and checking each field for validity.

The rules for validity are as in your first program, with the addition of a rule that specifies that each record must contain exactly 3 fields.

Your program should print out each valid record it reads.

The program should be able to raise an exception on invalid input, print out an error message with the line and what the error was, and continue running properly on the next line(s).

Answer 1

Thanks for the question.

Here is the completed code for this problem. 

Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. 

If you are satisfied with the solution, please rate the answer. 

Thanks

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# function takes in a name and validate if it meets all
# conditions , return True if all conditions are met False otherwise
def validateName(name):
    if len(name) > 20:
        print('Name should be less than 20 characters.')
        return False
    for letter in name.lower():
        if letter < 'a' or letter > 'z':
            print('Name contains invalid characters.')
            return False
    return True


# function takes in a score as string value
# validate the score is an integer and ranges between 1 and 100
# returns True if all conditions are meet False otherwise
def validateScore(score):
    try:
        result = int(score)
        if result < 1 or result > 100:
            print('Exam result should be between 1 and 100')
            return False
        else:
            return True
    except:
        print('Invalid number entered.')
        return False

# keep asking input from user until input meets all the condition
def getName(message):
    while True:
        name = input(message).lower()
        if validateName(name):
            return name.title()

# keep asking valid score from user until input meets all the condition
def getScore():
    while True:
        score = input('Enter exam result: ')
        if validateScore(score):
            return int(score)

# takes in the list of records user entered, the filename
# and saves the data in the file
def save_to_file(records, filename):
    with open(filename, 'w') as outfile:
        for record in records:
            outfile.write('{} {} {}\n'.format(record[0], record[1], record[2]))
    print('Data written to file: {} successfully.'.format(filename))

# reads data from file and validates the record contains valid entries
def read_file(filename):
    with open(filename, 'r') as infile:
        for line in infile.readlines():
            values = line.strip().split()
            if len(values) != 3:
                print('ERROR: {} contains not exactly 3 values'.format(line))
            elif validateName(values[0].strip()) and validateName(values[1].strip()) and validateScore(
                    values[2].strip()):
                print('VALID RECORD: {} {} {}'.format(values[0], values[1], values[2]))
            else:
                print('ERROR: {} contains either invalid name or exam score.'.format(line))

# main function , execution starts here
def main():
    records = []
    filename = 'customers.txt'
    while True:
        firstname = getName('Enter first name: ')
        lastname = getName('Enter last name: ')
        score = getScore()
        records.append([firstname, lastname, score])
        add_another = input('Do you want to add another record (Y/N): '.upper())
        if add_another == 'N':
            break

    save_to_file(records, filename)
    read_file(filename)


main()

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