How to round a non-floating point number?

Question

How do I round a non-floating point number? e.g. 9107609 down to 91 or to 911, etc.

`9107609/100000` or `9107609/10000` – Maroun Dec 17 '14 at 18:10 — Maroun, Dec 17 '14 at 18:10

score 5 · Answer 1 · edited May 23 '17 at 10:10

5

Divide by 100000 or 10000, respectively. C division rounds towards zero, so the numbers will always be rounded down. To round to the nearest integer, see this question.

edited May 23 '17 at 10:10

Community

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answered Dec 17 '14 at 18:14

Adrian

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Is "rounding down" equivalent to truncating the decimal? E.g. 1.9 gets "rounded down" to 1? – Chris Sprague Dec 17 '14 at 18:19

score 1 · Answer 2 · answered Dec 17 '14 at 18:16

1

Something like floor(number/(10^numberofdigitstocut)) or ceil(number/(10^numberofdigitstocut)) would do.

answered Dec 17 '14 at 18:16

kos

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score 0 · Answer 3 · answered Dec 17 '14 at 20:46

0

#include <math.h>

//returns n rounded to digits length
int round_int (int n, int digits)
{
   int d = floor (log10 (abs (n))) + 1; //number of digits in n

   return floor(n / pow(10, d-digits));
}

answered Dec 17 '14 at 20:46

Bence Gedai

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score 0 · Answer 4 · answered Dec 19 '14 at 04:42

0

To round, use a half way addition (if positive, else subtract 10000/2)

int rounded = (9107609 + 10000/2)/10000;

answered Dec 19 '14 at 04:42

chux - Reinstate Monica

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How to round a non-floating point number?

4 Answers4