Limit user input in python in special format

Question

Hi I would like to request a time from the user in the format "HH:MM" using the input() function.

Do you have an idea with which function I can ensure that the user only enters numbers and only the special character ":" and not e.g. ";".

I create a funtion:

def checkElements(time):
    symbole = ":"
    res_list = []
    allowedKeys = ["0","1","2","3","4","5","6","7","8","9"]
    sizeAllowedKeys = len(allowedKeys)
    if symbole in time:
        res_list.append(symbole)
        for i in range(sizeAllowedKeys):
            if allowedKeys[i] in time:
                res_list.append(allowedKeys[i])
            elif allowedKeys[i] not in time:
                #print("false input")
                pass
        if len(res_list) == 5:
            keyStatus = 0
        elif len(res_list) != 5:
            print("false input")
            keyStatus = 1
    else:
        print("false input")
        keyStatus = 1
    return keyStatus

But here I have the problem that it does not recognize already recognized digits twice. Also I think that the solution is not very clean.

Thank you and best regards

Answer 1

Try this:

def check(time):

    # time = 12:20
    # time.split(":") -> [12, 20]
    # "".join(time.split(":")) -> 1220
    if ":" in time and "".join(time.split(":")).isdigit(): 
        print("Great time")
    else:
        print("Wrong time")

check("12:20")