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round off number

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Join Date: Sep 2006

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vbcielle

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round off number

Oct 13th, 2006

how will i round off the return value to decimal place with tis function?

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
unsigned int CalculatePercentage(int TotalComponent, int PartialComponent){
return int((PartialComponent/TotalComponent)100);
}
unsigned int CalculatePercentage(int TotalComponent, int PartialComponent){
return int((PartialComponent/TotalComponent)100);
}

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Join Date: Jun 2005

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andor

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Re: round off number

Oct 13th, 2006

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Originally Posted by vbcielle

how will i round off the return value to decimal place with tis function?
Help with Code Tags

C Syntax (Toggle Plain Text)
unsigned int CalculatePercentage(int TotalComponent, int PartialComponent){
return int((PartialComponent/TotalComponent)100);
}
unsigned int CalculatePercentage(int TotalComponent, int PartialComponent){ return int((PartialComponent/TotalComponent)100); }

You must multiply with 100 (for multiplaying use *).

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vbcielle

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Re: round off number

Oct 13th, 2006

•

Originally Posted by andor

You must multiply with 100 (for multiplaying use *).

okie thanks but how can i round it off to one deciamal place?

for example

(PartialComponent/TotalComponent)*100
90/235=38.3 %

38.3 should be the return value

anyone? i shouldnt be using any math.h function etc.

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DavidRyan

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Re: round off number

Oct 13th, 2006

Try:

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floatValue = float(int(floatValue *  10 + 0.5)) / 10;

Please anyone, correct me if I am wrong. It is the best way for me to learn.

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andor

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Re: round off number

Oct 13th, 2006

•

Originally Posted by vbcielle

okie thanks but how can i round it off to one deciamal place?

for example

(PartialComponent/TotalComponent)*100
90/235=38.3 %

38.3 should be the return value

anyone? i shouldnt be using any math.h function etc.

Your func CalculatePercentage should return double or float instead of unsigned int, and to round read this

If you want to win, you must not loose (Alan Ford)

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bumsfeld

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Re: round off number

Oct 13th, 2006

The rounding is done in your display function. Here is C example:

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
// percent calculation, wants 100 * 90/235 --> 38.3 %
 
#include <stdio.h>
 
double CalculatePercentage(double TotalComponent, double PartialComponent)
{
    return 100*PartialComponent/TotalComponent;
}
 
int main()
{
   printf("100 * 90/235 --> %0.1f%c", CalculatePercentage(235, 90), '%');
 
   getchar();  // wait for key press
   return 0;
}
// percent calculation, wants 100 * 90/235 --> 38.3 %

#include <stdio.h>

double CalculatePercentage(double TotalComponent, double PartialComponent)
{
    return 100*PartialComponent/TotalComponent;
}

int main()
{
   printf("100 * 90/235 --> %0.1f%c", CalculatePercentage(235, 90), '%');
   
   getchar();  // wait for key press
   return 0;
}

And here is C++ example:

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 C Syntax (Toggle Plain Text) 
// percent calculation, wants 100 * 90/235 --> 38.3 %
 
#include <iostream>
#include <iomanip>
 
using namespace std;
 
double CalculatePercentage(double TotalComponent, double PartialComponent)
{
    return 100*PartialComponent/TotalComponent;
}
 
int main()
{
   cout.setf(ios::fixed);
   cout<< setprecision(1) << "100 * 90/235 --> " << CalculatePercentage(235, 90) << '%' << endl;
 
   cin.get();  // wait for key press
   return 0;
}
// percent calculation, wants 100 * 90/235 --> 38.3 %

#include <iostream>
#include <iomanip>

using namespace std;

double CalculatePercentage(double TotalComponent, double PartialComponent)
{
    return 100*PartialComponent/TotalComponent;
}

int main()
{
   cout.setf(ios::fixed);
   cout<< setprecision(1) << "100 * 90/235 --> " << CalculatePercentage(235, 90) << '%' << endl;
  
   cin.get();  // wait for key press
   return 0;
}

Last edited by bumsfeld; Oct 13th, 2006 at 4:31 pm.

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~s.o.s~

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Re: round off number

Oct 13th, 2006

The question is about rounding off the returned value and not rounding off while displaying. Read the first post.

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bumsfeld

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Re: round off number

Oct 13th, 2006

•

Originally Posted by ~s.o.s~

The question is about rounding off the returned value and not rounding off while displaying. Read the first post.

This does not make any sense, if the return value is double or float you can not guarantee precision to be 38.3 it most like will be 38.2999999 or something like that.

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~s.o.s~

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Re: round off number

Oct 13th, 2006

Try out something like this, though its a bit round about way, but should work:

 Help with Code Tags 
 C Syntax (Toggle Plain Text) 
double return_round( double value, double total )
{
    char buffer[BUFSIZ] = {'\0'} ;
    double percentage = ( value / total ) * 100 ;
    printf( "\nActual number: %lf", percentage ) ;
 
    sprintf(buffer, "%0.2f", percentage) ;
 
    if ( buffer[ strlen( buffer ) - 1 ] >= '5' )
        buffer[ strlen( buffer ) - 2 ] += 1 ;
    buffer[ strlen( buffer ) - 1 ] = '\0' ;
 
    printf( "\nThe rounded string is: %s", buffer ) ;
 
    return atof( buffer ) ;
}
double return_round( double value, double total )
{
    char buffer[BUFSIZ] = {'\0'} ;
    double percentage = ( value / total ) * 100 ;
    printf( "\nActual number: %lf", percentage ) ;

    sprintf(buffer, "%0.2f", percentage) ;

    if ( buffer[ strlen( buffer ) - 1 ] >= '5' )
        buffer[ strlen( buffer ) - 2 ] += 1 ;
    buffer[ strlen( buffer ) - 1 ] = '\0' ;

    printf( "\nThe rounded string is: %s", buffer ) ;

    return atof( buffer ) ;
}

Hope it helped, bye.

Last edited by ~s.o.s~; Oct 13th, 2006 at 5:16 pm.

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WaltP

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Re: round off number

#10

Oct 15th, 2006

I'm with bumsfeld on this one. You want as much precision as you can get throughout the program's calculations and only round for the display. You don't even want to round the number itself, just the display.

If you round prematurely, all your calculations will be slightly off. And the more calculations you do, the more inaccurate your answer.

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