The data types Single and Double
are VB6’s two floating point types; they’re used to store numerical values that
have digits to the right of the decimal point. The number of such digits can
vary (hence the name “floating point”) because the decimal point position
can vary. For example:
Differences between Double and Single
Most programmers know that type Double can hold larger
values than type Single, and Double also requires more space for storage—8 as
opposed to 4 bytes.
The most important difference between Double and Single is
the precision with which values can be represented. For instance, type Single
is limited to 7 digits; thus, these values are fine for a type Single:
However, if you try to store the value 123456789 in a type
Single, it is rounded to 7 digits: 123456800. Likewise, the value 1.23456789 is
truncated to 1.234568.
In contrast, type Double permits 15 digits of accuracy. So
for programs that do a lot of mathematical calculations, be sure to use type
Double when needed or the accuracy will suffer.
Note: The Visual
Basic help talks about a data type named Decimal with 28 digits of accuracy.
This sounds great but, unfortunately, it was never actually implemented.
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