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Python Python Basics (Retired) Things That Count Ints & Floats

Harsh Kumar Woike
Harsh Kumar Woike
204 Points
Posted by Harsh Kumar Woike
Harsh Kumar Woike
204 Points

floats

floats always behave like decimals as we use for money? how is it false?

1 Answer

Max Hirsh
Max Hirsh
16,773 Points
Max Hirsh
Max Hirsh
16,773 Points

This is false because of how computers work at a very basic level. Everything a computer does is in base 2 (a number system based on different powers of two, represented as a series of 1's and 0's), but the numbers we use in everyday life are base-10. Because of this, many computer representations of base-10 numbers are only approximations.

For example, 0.100 represented in base 2 is a weird infinite decimal, "0.0001100110011...(base-2)". Here's a link to the number in wolfram alpha: http://www.wolframalpha.com/input/?i=0.100+in+base+2

Because an infinitely long base-2 decimal number is required to represent a simple base-10 decimal number and computers have limited/finite space to store variables, the digital representation of 0.100 (base-10) is only approximate. Because of this, if you run this test:

0.100 * 10 == 1, the answer will be false because the floating point number 0.100 is only approximately 0.1, but not exactly. Sorry for the long-winded explanation but hope this information helps.