Error on == operator

[stef-pellegrino]

  decimal<2> x;

  x = 5.6;

  if (x == 5.6) {
      puts("ok");
  }

I get with vs2012, this error :

error C2678: binary '==' : no operator found which takes a left-hand operand of type 'dec::decimal' (or there is no acceptable conversion)

[vpiotr]

Such a comparison is not valid with both doubles and also with decimal + double. Use decimal_cast instead:

if (x == decimal_cast<2>("5.6")) {
  puts("ok");
}

[stef-pellegrino]

Ok, and code like this ?

bool operator==(double rhs) const {
  return (m_value == RoundPolicy::round(static_cast<double>(DecimalFactor<Prec>::value) * rhs));
}

[vpiotr]

This code is invalid:

• it performs implicit rounding during processing, which can result in decimal<2>(5.6) == 5.601

You should not store input values for decimal in double form at any phase, as this can cause some hard to track errors. Also "decimal_for_cpp" library is designed in this way so it doesn't perform roundings inside calculations (only during variable initialisation). This way it blocks using it with float/double in expressions which is invalid.

You can also use decimal_cast with double, but I would avoid that if possible. For storing values outside of decimal you can use getUnbiased() / setUnbiased() which is very fast.