Python def function assignment issue

Question

I was given an assignment in which I was supposed to make program which does different kind of calculations/ functions by giving the number of the function (must use function with def). And got seriously stuck with it.

1.

choice = int(input("Chosen function: "))
while choice != 0
if choice == 1:
    print("Sum of the list: ", summ_list(lista))
if choice == 2:
    print("Is the chosen number inside?: ", decide_if_in(lista, s))
.......
else:
    print("The program closes.")

If the user presses 0 the program should terminate. However to all my best effort if I make a while or for loop it will get stuck in an infinite loop thus I am unable to solve it.

2.

def decide_if_in():
    s = int(input("Which number do you think is in the list?: "))
    for d in s:
        if d == s:
             print("It is in the list")
        else:
            print("It is not in the list..")

Here it does work without the def tag but I cant make it work with it. The point would be I give it a number and it checks the list that is it inside the list?

Answer 1

In your example 1, you are not updating choice inside your loop. That is why it is stuck in infinite loop. You can write it as,

choice = int(input("Chosen function: "))
while choice != 0:
    if choice == 1:
        print("Sum of the list: ", summ_list(lista))
        choice = int(input("Chosen function: "))
    if choice == 2:
        print("Is the chosen number inside?: ", decide_if_in(lista, s))
        choice = int(input("Chosen function: "))
.......
    else:
        print("The program closes.")

A tiny bit of tip- in python, you can directly put functions in list or dictionary. So, you can do something like

def func1(arg1):
    #do something here
def func2(arg1):
    #do something else

func_dic = {1:func1, 2:func2}
choice = int(input("Whatever: "))
while choice != 0:
    print("Whatever: ", func_dic[choice](list))
                        ^^^^^^^^^^^^^^^^ -> function of choice here
print("close dialogue")

For your second code, your definition is wrong. You can simply do it by

def func_name(lista):
    s = int(input("Whatev: "))
    if s in lista:
        return "It's in"
    else:
        return "It's not in"

Answer 2

choice = int(input("Chosen function: "))
while 1: # Loops infinitely, using exit() to stop the script
    if choice == 1:
        print("Sum of the list: ", summ_list(lista))
    elif choice == 2: # Better to use elif
        print("Is the chosen number inside?: ", decide_if_in(lista))
    .....
    elif choice == 0:
        print("The program closes.")
        exit() # Stops the python script
    choice = int(input("Chosen function: ")) # Asking for input again

def decide_if_in(lista): # Taking the list as an arg
    s = int(input("Which number do you think is in the list?: "))
    if s in list:
        print("It is in the list")
    else:
        print("It is not in the list..")