when I perform 12*20/100, I get 2 as the output
but when I perform 12*(20/100), I get 0 as the output
So does anyone know why the brackets affect the output?
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Aditi Rawat
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3Because of **integer arithmetic** i.e. `integer/integer = integer`. Brackets have got nothing to do with it. – Aditi Rawat Dec 29 '17 at 17:50
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It is because (20/100) as integer division evaluates to 0. use (20.0/100) to get 0.2. Without parentheses you have 240 / 100 = 2 (as integer)
Patrick Artner
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In mathematics, parentheses don't matter for your expression.
But C++ computation (especially integer arithmetic) isn't mathematics. You already understand that, as you accept 12*20/100 being 2 instead of 2.4.
Setting parentheses defines what to compute first (as in mathematics), so 12*(20/100) first computes 20/100, giving 0, and then 12*0, giving 0.
Ralf Kleberhoff
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I disagree, not all calculation "in mathematics" happens in ℝ or whatever domain you had in mind. This kind of integer division goes all the way back to Euclid around 300BCE, it's certainly not just some unmathematical C++ quirk. – harold Dec 30 '17 at 00:07