Name
Option Strict Statement
Syntax
Option Strict [On | Off]
Description
Option
Strict
prevents VB
from making any
implicit data
type conversions that are narrowing since
narrowing conversions may involve data loss. For example:
Dim lNum As Long = 2455622 Dim iNum As Integer = lNum
converts a Long (whose value can range from
-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807) to an
Integer (whose value can range from 2,147,483,648 to 2,147,483,647).
In this case, even though no data loss would result from the
narrowing, Option
Strict
On
would still not allow the conversion and would
instead generate a compiler error. The reasoning here is that,
although particular narrowing operations may not lose data, there is
always the potential for data loss when working with
variables—that is, with symbolic representations of numbers
whose values are allowed to vary.
Rules at a Glance
If the
Option
Strict
statement is not present in a module,Option
Strict
isOff
.The default is
Option
Strict
On
. In other words, the statement:Option Strict On
is equivalent to the statement:
Option Strict
The
Option
Strict
statement must appear in the declarations section of a module before any code.Option Strict On
disallows all implicit narrowing conversions.Option
Strict
On
also causes errors to be generated for late binding, as well as for any undeclared variables, sinceOption
Strict
On
impliesOption
Explicit
On
.
Programming Tips and Gotchas
Although the setting of
Option
Strict
has no effect on BCL ...
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