Tools.h++ Manual

4-10 104011 Tandem Computers Incorporated

The French use “,” for the decimal point, and “.” for the digit group separator,

so this might display:

1.234567e+07 987654

1.234.567,89 987.654

Numbers with digit group separators are certainly easier to read.

Currency

Currency conversions are trickier, mainly because there is no standard way to

represent monetary values in a computer. We have adopted the convention

that such values represent an integral number of the smallest unit of currency

in use. For example, in the U.S, to represent the balance “$10.00”, you might

say

double sawbuck = 1000.;

This representation has the advantages of wide range, exactness, and

portability. By wide range, we mean that it can exactly represent values from

$0.00 up to (and beyond) $10,000,000,000,000.00. This is larger than any likely

budget. By exactness, we mean that representing monetary values without

fractional parts, you can perform arithmetic on them and compare the results

for equality:

This would not be possible if the values were naively represented, as for

instance "

price = 9.99;

By portability, we mean simply that

double

is a standard type, unlike

common 64-bit integer or BCD representations. Of course, ﬁnancial

calculations may still be performed on such other representations, but because

it is always possible to convert between them and

double

, this supports

everyone. In the future

RWLocale

may directly support some other common

representations as well.

double price = 999.; // $9.99

double penny = 1.; // $.01

assert(price + penny == sawbuck);