Python Validate User Input
Example 1
isalpha
while True:
name = input("Enter the player's name: ")
if name.isalpha() and len(name) > 1:
break
else:
print("Invalid name. Please enter a valid name with alphabetic characters only.")
print(f"The player's name is {name}.")
Example 2
integer
while True:
try:
home_runs = int(input("Enter the number of home runs: "))
if 0 <= home_runs <= 80:
break
else:
print("Please enter the correct number of home runs (0-80).")
except ValueError:
print("Invalid input. Please enter a whole number.")
print(f"The number of home runs is {home_runs}.")
Example 3
float
while True:
try:
average = float(input("Enter the player's batting average (0.000 - 0.500): "))
if 0.000 <= average <= 0.500:
break
else:
print("Please enter a batting average between 0.000 and 0.500.")
except ValueError:
print("Invalid input. Please enter a number between 0.000 and 0.500.")
print(f"The player's batting average is {average}.")
Example 4
custom invalid characters not using isalpha
invalid_chars = ('.', '/', '!', '@', '#', '1', '2', '3')
while True:
name = input("Enter the player's name: ")
invalid_chars_count = 0
for char in invalid_chars:
if char in name:
invalid_chars_count += 1
if invalid_chars_count > 0 or len(name) < 1:
print()
print("invalid!")
else:
break
print (name)
Example 5
date example
from datetime import datetime
Define the valid months for the baseball season
February (2) to October (10)
valid_months = list(range(2, 11))
while True:
game_date_input = input("Enter the baseball game date (MM/DD/YYYY): ")
try:
# Attempt to parse the date input
game_date = datetime.strptime(game_date_input, "%m/%d/%Y")
# Check if the month of the date is within the valid range
if game_date.month in valid_months:
print(f"Valid date: {game_date.date()}")
print("Thank you! The game date is set.")
break
else:
print("The date must be between February and October.")
except ValueError:
print("Invalid date format. Please enter the date in MM/DD/YYYY format.")
