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Math.round (from Poddar exam)

 
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from Poddar exam (http://members.theglobe.com/apoddar/questions.html)
Q25. What is the output of following
{
float f4 = -5.5f;
float f5 = 5.5f;
float f6 = -5.49f;
float f7 = 5.49f;
System.out.println("Round f4 is " + Math.round(f4));
System.out.println("Round f5 is " + Math.round(f5));
System.out.println("Round f6 is " + Math.round(f6));
System.out.println("Round f7 is " + Math.round(f7));
}
a)Round f4 is -6
Round f5 is 6
Round f6 is -5
Round f7 is 5
b)Round f4 is -5
Round f5 is 6
Round f6 is -5
Round f7 is 5
Answer: b
My question: Math.round(-5.5f) does yield �5, but is it correct result (from mathematical point of view?), I forgot...
 
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Look at it this way, 5.5 is 0.5 away from being 6.0. That is the starting point for 5.x to be rounded to 6.0. Now -5.5 is only 0.5 away from being -5.0, hence it is the starting point (inclusively) for -5.x to be rounded to -5.0.
Negtives are a bit confusing, and I hope this helps.
 
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Hi,
Note that given a float variable f,
Math.round(f) returns the value of
(int)Math.floor(f + 0.5f)
and given a double variable d,
Math.round(d) returns
(long)Math.floor(d + 0.5)
Hope this helps

Originally posted by Mapraputa Is:
from Poddar exam
My question: Math.round(-5.5f) does yield �5, but is it correct result (from mathematical point of view?), I forgot...


 
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