How to check if a float value is within a certain range and has a given number of decimal digits?

Question

How to check if a float value is within a range (0.50,150.00) and has 2 decimal digits?

For example, 15.22366 should be false (too many decimal digits). But 15.22 should be true.

I tried something like:

data= input()
if data in range(0.50,150.00):
   return True

Answer 1

Is that you are looking for?

def check(value):
    if 0.50 <= value <= 150 and round(value,2)==value:
        return True
    return False

---

Given your comment:

i input 15.22366 it is going to return true; that is why i specified the range; it should accept 15.22

Simply said, floating point values are imprecise. Many values don't have a precise representation. Say for example 1.40. It might be displayed "as it":

>>> f = 1.40
>>> print f
1.4

But this is an illusion. Python has rounded that value in order to nicely display it. The real value as referenced by the variable f is quite different:

>>> from decimal import Decimal
>>> Decimal(f)
Decimal('1.399999999999999911182158029987476766109466552734375')

According to your rule of having only 2 decimals, should f reference a valid value or not?

The easiest way to fix that issue is probably to use round(...,2) as I suggested in the code above. But this in only an heuristic -- only able to reject "largely wrong" values. See my point here:

>>> for v in [ 1.40,
...            1.405,
...            1.399999999999999911182158029987476766109466552734375,
...            1.39999999999999991118,
...            1.3999999999999991118]:
...     print check(v), v
...
True 1.4
False 1.405
True 1.4
True 1.4
False 1.4

Notice how the last few results might seems surprising at first. I hope my above explanations put some light on this.

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As a final advice, for your needs as I guess them from your question, you should definitively consider using "decimal arithmetic". Python provides the decimal module for that purpose.