How can I prove that a value from input is a number in Python?

Question

For a task I had to write a programm the programm functions nicely so I dont have a problem there. But I have to use input() and than I have to prove if the type is correct. I only needs integer but the type of input(5) is a str. Althought I need a int. But if use int(input()) thats also dont work because I want that my programm says this is a str or a float and because of this we cant move on. So that the programm now this is a number or not

I did try with only input() that were all Strings regardless of the content and i know why this is so but I dont like it. Then I tried int(input()) but this only works if I use actually only numbers. But I have also to type in strings and floats and then the programm should only say it is the wrong type but shouldnt print out an error message

`in = input()` then try to convert `in` to an integer. If it fails try to convert it to a floating point number, if it succeeds report it as such, otherwise report as invalid string. — Some programmer dude, Nov 28 '22 at 07:42
As for catching conversion errors, read more about *exceptions*. — Some programmer dude, Nov 28 '22 at 07:42
Does this answer your question? [Identifying the data type of an input](https://stackoverflow.com/questions/22199741/identifying-the-data-type-of-an-input) — mkrieger1, Nov 28 '22 at 07:51

score 0 · Answer 1 · answered Nov 28 '22 at 07:45

0

s = input()


try:
    print(int(s))

except:
    print("not int")

answered Nov 28 '22 at 07:45

rtoth

67
4

It's better so specify what exception is expected. In this case ValueError – ShadowCrafter_01 Nov 28 '22 at 08:28
I just wanted to give him a simple example, but you are right – rtoth Nov 28 '22 at 08:40
**do not use bare except clauses for this** – juanpa.arrivillaga Nov 28 '22 at 08:44

Usman Arshad · Accepted Answer · 2022-11-28T08:44:24.540

-1

We can achieve this by using eval only.

e.g:

val = input()
try:
    val = eval(val)
except NameError:
    pass

In try it will try to return the exact data type, like int, float, bool, dict, and list will works fine but if input value is string it will go to NameError and print val is string.

if we want to handle some case on the basis of data type, we can do it using this:

if isinstance(val, int):
    print("This is integer")

if isinstance(val, float):
    print("This is float")

if isinstance(val, str):
    print("This is string")

similary for others as well.

edited Nov 28 '22 at 08:44

answered Nov 28 '22 at 07:57

Usman Arshad

537
11

Thank you this helps me a lot I guess I will use eval more often in the future now – Yanoisa Nov 28 '22 at 09:36
It's my pleasure. – Usman Arshad Nov 28 '22 at 09:40

How can I prove that a value from input is a number in Python?

2 Answers2