to solve phone number validation in python(regular expression) i use this code ,but didn't get the positive result,what's wrong

Question

impot re
a = str(input())
pattern = r"^[189][0-9]+"
if re.match(pattern,a):
if len(a) == 8:
print("valid")
else:
print("invalid")
else:
print("invalid)

Answer 1

Consider a string of length 8 such as "136ghg45", it will output valid for it as your pattern matches "136" .

Instead use the following pattern ,

import re
a = input()

pattern = r"[189][0-9]{7}quot;
if re.match(pattern,a):
print("valid")
else:
print("invalid")

In the above pattern,

{7} will check for exact 7 occurences of number after first number which makes it a total 8 .

"quot; will check if string is ending with only 8 characters in total (so no need of checking length as an extra step).

𝗙𝗬𝗜 : Input function returns a string only . Also there was a syntax error and spelling mistake in your code that i corrected .

Answer 2

It also doesn't work bro

Answer 3

I've write this more simpe:

import re
p = r'^[189]'
a = str(input())
if re.match(p,a) and len(a) == 8:
print('valid')
else:
print('invalid')

Answer 4

# oneliner:

print("Valid" if re.fullmatch("[189].{7}", input()) else "Invalid")