setting the number of decimal places

[Maurader]

Is there a way I can set the number of decimal places in a double?

I need to be able to take two doubles, that are the same up to a certain of decimal places, and compare them only up to that point (so truncate after a certain error level)

 

[Guest_imported]

I think setw( some integer);

 

[Maurader]

but that only formats the output stream...i need to do calculations with the truncated number

 

[Leibnitz]

Try this:

#include <iostream.h>
#include <stdio.h>
#include <stdlib.h>
void main()
{
double number;
char buffer[20];
int precval;
int count = 0;
bool counting = false;
int i = 0;
char *pEnd;
cout<<&quot;number = &quot;;
cin>>number;
cout<<&quot;precision value = &quot;;
cin>>precval;
sprintf(buffer,&quot;%lf&quot;, number );
while( buffer != '\0' )
{
if( buffer == '.' )
counting = true;
if( counting )
count++;
if( count == precval + 1 )
break;
i++;
}
buffer[i+1] = '\0';
number = strtod( buffer, &pEnd );
cout<<&quot;number' = &quot;<<number;
}

 

[jtm111]

ROUND A NUMBER TO THE NEAREST WHOLE INTEGER
floatValue = floor(floatValue*1+0.5)/1;

ROUND A NUMBER TO THE NEAREST 10th
floatValue = floor(floatValue*10+0.5)/10;

ROUND A NUMBER TO THE NEAREST 100th
floatValue = floor(floatValue*100+0.5)/100;

etc.

 

[Maurader]

wicked, thx!