How to indicate IF condition that only include INT

Question

I have just started out learning python and needed some help.

Let's say I have created a simple calculator whereby all it do is just finding the average of the sum.

a = input("First number")
b = input("Second number")
c = input("Third number")

if():
    avg = (a+b+c)/3
print'Average:%.2f' %avg
else:
  ............

How am I supposed to write the if condition to indicate that IF and only if a b and c are int.

I put it as input() because I want to give it an option whereby people who may keyed in something that is not a number such as 'ABC'.

Possible duplicate of [Checking whether a variable is an integer or not](https://stackoverflow.com/questions/3501382/checking-whether-a-variable-is-an-integer-or-not) — VMRuiz, Sep 13 '17 at 06:55
Don't use `input` in python2. You should use `a = int(raw_input("First number"))` etc. — John La Rooy, Sep 13 '17 at 06:59
Well, `input()` returns string, so you can check it using `isdigit()` and if it returns True, then You can convert it to a int — JJAACCEeEKK, Sep 13 '17 at 07:00
@JohnLaRooy I didn't want it to convert it to INT upon keying in. I am leaving an option whereby people who key in something that is not a number so I will produce an error message out. — Luke, Sep 13 '17 at 07:11
Possible duplicate of [How to check if string input is a number?](https://stackoverflow.com/questions/5424716/how-to-check-if-string-input-is-a-number) — Gall, Sep 13 '17 at 08:03

Ahmed Elkoussy · Answer 1 · 2017-09-13T07:10:58.627

0

The if condition to test a, b, c are integers will be:

if (isinstance( a , int ) and isinstance( b , int ) and isinstance( c , int )):

For example , code like this:

a = "asdasd"
b = 2
c = 3
# if(int(a) and int(b) and int(c)):
if (isinstance( a , int ) and isinstance( b , int ) and isinstance( c , int )):
    print("integers")
else:
    print("not integers")

Output for the above example:

not integers

edited Sep 13 '17 at 07:10

answered Sep 13 '17 at 07:00

Ahmed Elkoussy

8,162
10
60
85

@TomKarzes , sorry , I searched for it and tested it so I felt it was correct. thanks for feedback , should I remove this answer or improve it ? – Ahmed Elkoussy Sep 13 '17 at 07:05
@TomKarzes I corrected the answer , please check , thanks – Ahmed Elkoussy Sep 13 '17 at 07:11
That's better, although in Python 2 (which OP is apparently using), it will not recognize longs as integers. In Python 2, you can use `isinstance(v, (int, long))`. – Tom Karzes Sep 13 '17 at 07:24
@TomKarzes thanks for feedback & explaining I hope whoever downvoted the wrong answer will upvote the updated correct one. – Ahmed Elkoussy Sep 13 '17 at 07:52
It wasn't me, sorry. – Tom Karzes Sep 13 '17 at 10:11

score 0 · Accepted Answer · answered Sep 13 '17 at 07:03

0

if a.isdigit() and b.isdigit() and c.isdigit():
     avg = (int(a) + int(b) + int(c))/3

answered Sep 13 '17 at 07:03

JJAACCEeEKK

194
1
11

``isdigit()`` will not work for negative integers as it only checks for the presence of digit characters. – Gall Sep 13 '17 at 08:07
please explain why this helps with the problem in the Q. – loki Sep 13 '17 at 08:31

Aleksandr Sokolov · Answer 3 · 2017-09-14T09:04:16.097

0

Try this for every variable, first check is it INT , second check is it STR representing INT:

if isinstance(a, int) or (str(a)[0] == '-' and str(a)[1:].isdigit()) or str(a).isdigit():
    print('integer')
else:
    print('not integer')

replace bc if you have integer below zero isdigit() return false. Python 2.7

edited Sep 14 '17 at 09:04

answered Sep 13 '17 at 07:44

Aleksandr Sokolov

1
2

That's an interesting way to check for an integer but the sign can only be the first character and appear once. Right now you will replace multiple characters wherever they are in the string causing false positives. I guess you could go with something like ``(a[0] == '-' and a[1:].isdigit()) or a.isdigit()``. – Gall Sep 13 '17 at 08:15
yeah, u right, i missed that there could be multiple '-' at any index, corrected answer – Aleksandr Sokolov Sep 13 '17 at 11:10

score -1 · Answer 4 · answered Sep 13 '17 at 07:00

-1

import types

if type(a) == types.IntType and type(b) == types.IntType and type(c) == types.IntType:

     ....

     ....

answered Sep 13 '17 at 07:00

Deepaklal

119
4

How to indicate IF condition that only include INT

4 Answers4