Checking whether a variable is an integer or not [duplicate]

Answer 1

A simple method I use in all my software is this. It checks whether the variable is made up of numbers.

test = input("Enter some text here: ")
if test.isdigit() == True:
   print("This is a number.")
else:
   print("This is not a number.")

Answer 2

If you really need to check then it's better to use abstract base classes rather than concrete classes. For an integer that would mean:

>>> import numbers
>>> isinstance(3, numbers.Integral)
True

This doesn't restrict the check to just int, or just int and long, but also allows other user-defined types that behave as integers to work.

Answer 3

>>> isinstance(3, int)
True

See here for more.

Note that this does not help if you're looking for int-like attributes. In this case you may also want to check for long:

>>> isinstance(3L, (long, int))
True

I've seen checks of this kind against an array/index type in the Python source, but I don't think that's visible outside of C.

Token SO reply: Are you sure you should be checking its type? Either don't pass a type you can't handle, or don't try to outsmart your potential code reusers, they may have a good reason not to pass an int to your function.

Answer 4

I was writing a program to check if a number was square and I encountered this issue, the code I used was:

import math
print ("this program will tell you if a number is square")
print ("enter an integer")
num = float(input())
if num > 0:
    print ("ok!")
    num = (math.sqrt(num))
    inter = int(num)
    if num == inter:
            print ("It's a square number, and its root is")
            print (num)
    else:
            print ("It's not a square number, but its root is")
            print (num)
else:
    print ("That's not a positive number!")

To tell if the number was an integer I converted the float number you get from square rooting the user input to a rounded integer (stored as the value ), if those two numbers were equal then the first number must have been an integer, allowing the program to respond. This may not be the shortest way of doing this but it worked for me.

Answer 5

It is very simple to check in python. You can do like this:

Suppose you want to check a variable is integer or not!

## For checking a variable is integer or not in python

if type(variable) is int:
     print("This line will be executed")
else:
     print("Not an integer")

Answer 6

A more general approach that will attempt to check for both integers and integers given as strings will be

def isInt(anyNumberOrString):
    try:
        int(anyNumberOrString) #to check float and int use "float(anyNumberOrString)"
        return True
    except ValueError :
        return False

isInt("A") #False
isInt("5") #True
isInt(8) #True
isInt("5.88") #False *see comment above on how to make this True