Exercise 12-06:
Create a function using pattern_check that validates cell phone numbers. A cell phone has 9 digits after the LDC (for example, (92)99812-1103).
Answer:
##############################################################################
# Python From Scratch
# Author: Nilo Ney Coutinho Menezes
# Editora Novatec (c) 2010-2025 - LogiKraft 2025
# Site: https://pythonfromscratch.com
# ISBN: 978-85-7522-949-1 (Paperback), 978-85-7522-950-7 (hardcover), 978-85-7522-951-4 (ebook)
#
# File: chapter 12/exercise-12-06.py.py
##############################################################################
# Functions number, sequence and check pattern from listing 12.5
from functools import partial
def number(input, min_qty, max_qty):
num = 0
for character in input:
if character.isnumeric():
num += 1
else:
break
if min_qty <= num <= max_qty:
return num, 0, num - 1
else:
return -1, -1, -1
def sequence(input, pattern):
position, max_position = 0, len(pattern)
for character in input:
if character == pattern[position]:
position += 1 # Same characters, test next character
else:
break # Out of sequence
if position == max_position: # Found entire sequence
return 1, 0, position - 1
return -1, -1, -1
def check_pattern(input, patterns):
position = 0
for pattern in patterns:
found, _, end = pattern(input[position:])
if found > 0:
position += end + 1
else:
return -1, -1, -1
return 1, 0, position - 1
def cell_number(input):
pattern = [
partial(sequence, pattern="("),
partial(number, min_qty=2, max_qty=3),
partial(sequence, pattern=")"),
partial(number, min_qty=5, max_qty=5),
partial(sequence, pattern="-"),
partial(number, min_qty=4, max_qty=4),
]
found, _, _ = check_pattern(input, pattern)
return found > 0
inputs = [
"(92)99999-9999", # Yes
"(11)99999-999", # No
"(2)99999-9999", # No
"(12)9999999999", # No
"(312)9999999999", # No
"(312)99999-9999", # Yes
]
for input in inputs:
print(f"{input}: is it a cell number? {'Yes' if cell_number(input) else 'No'}")