How can I only allow the input of numbers using exception handling?

Question

I’m still learning python and I’m trying to figure out how to only allow numerical input using try except. How would I do this?

My code:

def main():
    
    print("College Classification")
    print("")
    credits = float(input("Enter number of credits: "))
    if credits > 0 and credits <= 7:
        print("The classification is Freshman") 
    elif credits > 7 and credits <= 16:
        print("The classification is Sophomore")
    elif credits > 16 and credits <= 25:
        print("The classification is Junior")
    elif credits > 25:
        print("The classification is Senior")
    else:
        print("Error")
    input("")
    
if __name__ == "__main__":
    main()

Asked By: juniorsandwich

||

Source

Answer 1

Update related line to this:

credits = 0
try:
    credits = float(input("Enter number of credits: "))
except ValueError:
    print("unsupported input")
    return

Answered By: Majid

Answer 2

You simply need to declare the input variable. Try to convert it, and catch an exception. If the code fails to convert the input to a float, it will remain 0 and return to the top of the loop.

def main():
    
    print("College Classification")
    print("")
    credits = 0
    while credits == 0:
        try:
            credits = float(input("Enter number of credits: "))
        except:
            print("Please enter a valid number")
    if credits > 0 and credits <= 7:
        print("The classification is Freshman") 
    elif credits > 7 and credits <= 16:
        print("The classification is Sophomore")
    elif credits > 16 and credits <= 25:
        print("The classification is Junior")
    elif credits > 25:
        print("The classification is Senior")
    else:
        print("Error")
    input("")
    
if __name__ == "__main__":
    main()

Answered By: Dylan

How can I only allow the input of numbers using exception handling?

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