Python check int in range

Just like the code in your question, this will work both in Python 2.x and 3.x.

He doesn't have to say which he's using; the fact that he's doing int(input pretty much proves it's Py3.

@abarnert: It hints at it, but doesn't prove anything. I only write Python 2.x, yet routinely use parentheses with print() . I'd also write int(input(. )) here, just to make the code future-proof.

With all due respect, someone who's clearly a beginner is not being taught to write Python 2 code that usually also works in Python 3; he's being taught to write Python 3 code.

@abarnert: I think we are debating a trivial, irrelevant issue. I therefore propose that we leave it at that.

First, you have to know how to check whether a value is in a range. That's easy:

Almost a direct translation from English. (This is only a good solution for Python 3.0 or later, but you're clearly using Python 3.)

Next, if you want to make them keep trying until they enter something valid, just do it in a loop:

for i in range(total): while True: n = int(input("Enter a test score >> ")) if n in range(0, 101): break myList.append(n) 

Again, almost a direct translation from English.

But it might be much clearer if you break this out into a separate function:

def getTestScore(): while True: n = int(input("Enter a test score >> ")) if n in range(0, 101): return n for i in range(total): n = getTestScore() myList.append(n) 

As f p points out, the program will still "just end with a error" if they type something that isn't an integer, such as "A+". Handling that is a bit trickier. The int function will raise a ValueError if you give it a string that isn't a valid representation of an integer. So:

def getTestScore(): while True: try: n = int(input("Enter a test score >> ")) except ValueError: pass else: if n in range(0, 101): return n 

Источник

Assert an integer is within range

I am writing some unittests in python that are testing if I receive an integer. However sometimes this integer can be off by 1 or 2 and I don't really care. Essentially I want to be able to assert that the received integer is within a certain range, something like:

self.assertBetween(998, 1000, my_integer) 

Whether you use 1 or 2 asserts depends on what you really want to know and communicate. If you only care that my_integer is between the limits, one assert is a cleaner more concise means to test and communicate that to the next guy looking at the code (which maybe you in 3 months). If instead there is a good reason to know if my_integer is below 1000 separately to also knowing if my_integer is above 998, then it makes more sense to use 2 asserts.

4 Answers 4

@Yep_It's_Me: you asked if there's any benefit to this over your two separate conditionals. Yes. It's more concise, clearer, and more efficient (one function call instead of two).

@JohnZwinck while I agree this is shorter, I do not think this is something I would recommend because it has the same drawback as two assertTrue s. You lose verbosity of FAIL-message. With assertTrue , you'll get AssertionError: False is not true , which is not very helpful. I prefer to see what's wrong, so I would rather use assertGreaterEqual(my_integer, 998); assertLessEqual(my_integer, 1000) - that way you'll know what's wrong immediately (e.g.: AssertionError: 100 not greater or equal to 998 ).

the error message with this assertion wouldn't tell what was the value of my_integer or the limits (usually you don't have hard-coded limits like these). so I'd prefer the assertBetween method in @JanSpurny's answer.

Python has a built in function you may use for this: assertAlmostEqual .

self.assertAlmostEqual(myinteger, 999, delta=1) # is equivalent to self.assertTrue(998  

AssertionError: False is not true 

import unittest class BetweenAssertMixin(object): def assertBetween(self, x, lo, hi): if not (lo  

====================================================================== FAIL: test_too_high (__main__.Test1) ---------------------------------------------------------------------- Traceback (most recent call last): File "example.py", line 19, in test_too_high self.assertBetween(1001, 998, 1000) File "example.py", line 8, in assertBetween raise AssertionError('%r is not between %r and %r' % (x, lo, hi)) AssertionError: 1001 is not between 998 and 1000 ====================================================================== FAIL: test_too_low (__main__.Test1) ---------------------------------------------------------------------- Traceback (most recent call last): File "example.py", line 16, in test_too_low self.assertBetween(997, 998, 1000) File "example.py", line 8, in assertBetween raise AssertionError('%r is not between %r and %r' % (x, lo, hi)) AssertionError: 997 is not between 998 and 1000 ---------------------------------------------------------------------- 

. def test_no_custom_assert(self): my_integer = 100 self.assertGreaterEqual(my_integer, 998) self.assertLessEqual(my_integer, 1000) . 

====================================================================== FAIL: test_no_custom_assert (__main__.Test1) ---------------------------------------------------------------------- Traceback (most recent call last): File "example.py", line 23, in test_no_custom_assert self.assertGreaterEqual(my_integer, 998) AssertionError: 100 not greater than or equal to 998