How to restart a python program due to invalid input from the user

Question

I wanted to get some user input on a seat number on a train I wanted the program to check if the seat is valid( ie more than available seats. Eg: inputted seat: 101, seat limit: 100 ). If the seat no. is valid I want the program to continue and if invalid to ask again for the seat number.

import sys

seat = int(input("Seat Number: "))  # The seat number inputted by the user

if seat > 100:
    print("Seat limit exceeded")
    # restart?

If the seat is more than 100 I want the program to ask again for a seat no.

Answer 1

You can reverse the logic, use an infinite loop, and break when a valid seat number is inputted (ie, keep asking for input and stop when given a valid one):

while True:   # infinite loop
    seat = int(input("Seat Number: "))  # The seat number inputted by the user
    if seat <= 100:
        break
    print("Seat limit exceeded")

# code to be executed after a valid input is given

Answer 2

while True:
    seat = int(input("Seat Number: "))
    if seat > 100:
        print("Seat limit exceeded, choose another one")
    else:
        print("Seat is valid")
        break

output:

Seat Number: 110
Seat limit exceeded, choose another one
Seat Number: 45
Seat is valid

Process finished with exit code 0

Answer 3

seat = int(input("Seat Number: "))

while(seat < 0 or seat > 100):
    print('Invalid seat Number')
    seat = int(input("Seat Number: "))