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hacksign23
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Posts: 404
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 Posted: Sat May 30, 2009 7:22 pm Post subject: [C++] Help with roundING! |
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help with this:
| Code: |
double round(double input, int place){//rounds to place's digit
input *= 10^place;
int i2;
double istack;
i2 = (int)floor(input);
istack = input - (double)i2;
if (istack <= 0.4){
input = floor(input);
input /= 10^place;
return input;
}
if (istack >= 0.5) {
input = ceil(input);
input /= 10^place;
return input;
}
return input;
}
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there's a problem.
ex:
input:
double chicken = round(222.33333,2);
double is 222.375
got any ideas? thanks.
when debugging, i get chicken as 222.33333999999999
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&Vage
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Jani
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| Posted: Sun May 31, 2009 10:52 am Post subject: Re: [C++] Help with roundING! |
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| Are you sure how to use powers in C/C++?
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hacksign23
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Joined: 26 Nov 2006
Posts: 404
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| Posted: Mon Jun 01, 2009 7:45 pm Post subject: |
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shiat, that's not right, is it o_o?
lol yup. thanks. silly me.
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Last edited by hacksign23 on Mon Jun 01, 2009 7:54 pm; edited 1 time in total |
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oib111
I post too much
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Location: you wanna know why?
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| Posted: Mon Jun 01, 2009 7:46 pm Post subject: |
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^ is the xor operator, not the power operator.
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hacksign23
Master Cheater
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Joined: 26 Nov 2006
Posts: 404
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| Posted: Fri Jun 05, 2009 2:04 am Post subject: |
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okay, i have a function for rounding.
it rounds to place's place.
ex:
input = 22.312
place = 1
output = 22.3
any help?
thanks
double round(double input, int place){//rounds to place's place. haha :3
int iinput;
int iinput2;
double dinput;
double dstack;
iinput = (int)floor(input);
dinput = input-iinput;
dinput *= pow((double)10,place);
iinput2 = (int)floor(dinput);
dstack = dinput;
dstack -= iinput2;
if (dstack <=0.4) {
dinput = floor(dinput);
dinput /= pow((double)10,place);
input = iinput + dinput;
}
if (dstack >=0.5) {
dinput = ceil(dinput);
dinput /= pow((double)10,place);
input = iinput + dinput;
}
return input;
}
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LolSalad
Grandmaster Cheater
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Joined: 26 Aug 2007
Posts: 988
Location: Australia
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| Posted: Fri Jun 05, 2009 4:15 am Post subject: |
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| Code: | #include <cmath>
double round(double input, int places) {
double mul = pow(10.0, places);
double m = floor(input * mul);
if (floor(input * mul * 10) - m * 10 > 4)
return (m + 1) / mul;
else
return m / mul;
} |
That is what I would do.
| Code: | for (int i = 6; i > 0; i--) {
cout << round(274.285327, i) << '\n';
} |
Outputs
| Code: | 274.285327
274.28533
274.2853
274.285
274.29
274.3 |
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