python check for input code example

Example 1: python check if string is in input

try:
   val = int(userInput)
except ValueError:
   print("That's not an int!")

Example 2: python check if input() gives error

try:
    # Note: Python 2.x users should use raw_input, the equivalent of 3.x's input
    age = int(input("Please enter your age: "))
except ValueError:
    print("Sorry, I didn't understand that.")
else:
	if age >= 18: 
    	print("You are able to vote in the United States!")
	else:
    	print("You are not able to vote in the United States.")

Example 3: python double check if wants to execute funtion

def get_non_negative_int(prompt):
    while True:
        try:
            value = int(input(prompt))
        except ValueError:
            print("Sorry, I didn't understand that.")
            continue

        if value < 0:
            print("Sorry, your response must not be negative.")
            continue
        else:
            break
    return value

age = get_non_negative_int("Please enter your age: ")
kids = get_non_negative_int("Please enter the number of children you have: ")
salary = get_non_negative_int("Please enter your yearly earnings, in dollars: ")