input check help!

[bntayfur]

Hello, i am new to Python so i couldn't figure out how to check the input.

I want to get an input from the user(integer or float) and want to give an error message when it enters anything else(letter or any special character).

So far i know this works for the integer:

while True :    

    try:
        x = int(input('please enter an integer: '))
        print(x)
        break
    
    except ValueError: 
       print('not valid')

First can someone please explain the logic of this. I didn't understand it thoroughly.

But if i want it to accept decimal numbers as well integers what should i write? (very basically cause i am new)

Here are some of the things i tried which none of them worked.
1)

radius= input("enter a number: ")
if isinstance(radius,float): 
    print(radius)
elif isinstance (radius,int):
    print(radius)
else:    
    print("Not a number")

2)

radius= input("enter number: ")
if isinstance(radius,numbers.Real): 
    print(radius)
    else:
        print("not number")

3)

radius= input("enter number: ")
  if type(radius) in (float,int):
    print(radius)
  else:
    print("not a number")

4)

x=input('please enter integer: ')
if type(x) is int:
    print(x)

elif type(x) is float:
    print(x)
    
else:
    print('error')

5)

x=input('please enter integer: ')

if not type(x) is int: 
    raise TypeError('only numbers allowed')