Re: Rounding double

From:

Marco Manfredini <ok_nospam_ok@phoyd.net>

Newsgroups:

comp.lang.c++,comp.lang.c

Date:

Thu, 22 Nov 2007 17:24:27 +0100

Message-ID:

<1289630.EzYhzmucdD@technoboredom.net>

jacob navia wrote:

md wrote:

On Nov 22, 4:49 pm, suresh <mail2msur...@gmail.com> wrote:

On Nov 22, 10:39 am, md <mojtaba.da...@gmail.com> wrote:> Hi

Does any body know, how to round a double value with a specific
number of digits after the decimal points?
A function like this:
RoundMyDouble (double &value, short numberOfPrecisions)

{
int p = pow(10, numberOfPrecisions);
value = (int)(value * p + 0.5) / (double)p;

}- Hide quoted text -

- Show quoted text -

I tried that before but it does not work!

md

This can go beyond 9:
#include <stdio.h>
#include <math.h>

void RoundMyDouble (long double *value, short numberOfPrecisions)

{
long long p = powl(10.0L, numberOfPrecisions);
*value = (long long)(*value * p + 0.5L) / (double)p;
}

I have floor(). It even goes past 11!

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