Phone Number

Phone Number Formatting

Challenge Difficulty: Medium | Estimated completion time: ~15 minutes

Create a function that takes a list of 10 numbers (between 0 and 9) and returns a string of those numbers formatted as a phone number (e.g. (555) 555-5555).

Examples

format_phone_number([1, 2, 3, 4, 5, 6, 7, 8, 9, 0])
output = "(123) 456-7890"
 
format_phone_number([5, 1, 9, 5, 5, 5, 4, 4, 6, 8])
output = "(519) 555-4468"
 
format_phone_number([3, 4, 5, 5, 0, 1, 2, 5, 2, 7])
output = "(345) 501-2527"

Notes

Don’t forget the space after the closing parenthesis.

Solution

Python

def format_phone_number(digits: list[int]) -> str: """ Format a list of 10 digits as a phone number string. Args: digits: List of 10 integers (0-9) representing phone number digits. Returns: Formatted phone number string in format (XXX) XXX-XXXX. Examples: >>> format_phone_number([1, 2, 3, 4, 5, 6, 7, 8, 9, 0]) '(123) 456-7890' >>> format_phone_number([5, 1, 9, 5, 5, 5, 4, 4, 6, 8]) '(519) 555-4468' """ area_code = "".join(str(digit) for digit in digits[0:3]) prefix = "".join(str(digit) for digit in digits[3:6]) line_number = "".join(str(digit) for digit in digits[6:10]) return f"({area_code}) {prefix}-{line_number}" if __name__ <span class="text-highlight"> "__main__": # Test cases assert format_phone_number([1, 2, 3, 4, 5, 6, 7, 8, 9, 0]) </span> "(123) 456-7890" assert format_phone_number([5, 1, 9, 5, 5, 5, 4, 4, 6, 8]) <span class="text-highlight"> "(519) 555-4468" assert format_phone_number([3, 4, 5, 5, 0, 1, 2, 5, 2, 7]) </span> "(345) 501-2527" print("All test cases passed!")

Output