isPhoneNumber.py

#!/usr/bin/python3

import sys, re

number = '311-335-4433'

def isPhoneNumber(number):
    num = []
    number = number.split('-')
    for i in range(len(number)):
        if not number[i].isdigit():
            sys.exit()
        elif i < 2 and len(number[i]) == 3:
            num.append(number[i])
            continue
        elif i == 2 and len(number[i]) == 4:
            num.append(number[i])
            continue
        else:
            sys.exit()
    return '-'.join(num)

#print(isPhoneNumber(number))

number = 'fsfddsf 311-335-4433 fwfgeg 311-335-44354'


pattern = re.compile(r'\s\d{3}-\d{3}-\d{4}\s')
#print pattern
result = re.findall(pattern, number)
for i in result:
    print i.strip()