How should my program create an error if a negative integer entered? (python)

Question

while True:
    try:
        name=str(input("Enter your name="))
        age=int(input("Enter your age="))

    except ValueError:
        print("error!! please enter the values again")
        continue
    else:
        break

current_year=int(input("What is the current year you are living in="))

n=100-age
x=n+current_year
print(name,"",x,"is the year you will turn 100")

So how do I create an error msg for my use if he/she enter a negative number for the age, such that it allows the user to re-input the age.

Answer 1

Add a while loop which asks if the age is smaller than zero. If this condition is satisfied (the user entered a negative digit), the loop will go on (it will ask for a new input):

while True:
    try:
        name=input("Enter your name=")
        age=int(input("Enter your age="))
        while age < 0:
            age=int(input("Enter your age="))
        current_year=int(input("What is the current year you are living in="))

    except ValueError:
        print("error!! please enter the values again")
        continue
    else:
        break

n=100-age
x=n+current_year
print(name,"",x,"is the year you will turn 100")

Answer 2

I would try something using a while loop.

while age < 0:
    age=int(input("Enter your age="))
    if age < 0:
        print('try again')

We keep on taking user's age until they enter something above 0.