$//$ This program demonstrates how to safely test a floating$-$point number

$//$ to see if it is$,$ for all practical purposes, equal to some value.

#include

#include

using namespace std;

int main$()$

$\{$

double result $=\mathrm{.}666667*6\mathrm{.}0$;

$//2/3$ of $6$ should be $4$ and, if you print result, $4$ is displayed.

cout $<<$ "result $="<<$ result $<<$ endl;

$//$ However, internally result is NOT precisely equal to $4.$

$//$ So test to see if it is "close" to $4.$

if $($result $==4\mathrm{.}0)$

cout $<<$ "result DOES equal $4!"<<$ endl;

else

cout $<<$ "result DOES NOT equal $4!"<<$ endl;

return $0$;