OPTION EXPLICIT: Difference between revisions
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* The use of [[OPTION _EXPLICIT]] does also enforce the requirement to [[DIM]] or [[REDIM]] any arrays before first use, no extra [[OPTION _EXPLICITARRAY]] is needed. | * The use of [[OPTION _EXPLICIT]] does also enforce the requirement to [[DIM]] or [[REDIM]] any arrays before first use, no extra [[OPTION _EXPLICITARRAY]] is needed. | ||
* Enable [[OPTION _EXPLICIT]] temporarily even if a program source file doesn't contain the directive by specifying the '''-e''' switch when compiling via command line (''qb64 -c file.bas -e''). | * Enable [[OPTION _EXPLICIT]] temporarily even if a program source file doesn't contain the directive by specifying the '''-e''' switch when compiling via command line (''qb64 -c file.bas -e''). | ||
=== Errors === | === Errors === | ||
* If used, [[OPTION _EXPLICIT]] must be the very first statement in your program. No other statements can precede it (except for | * If used, [[OPTION _EXPLICIT]] must be the very first statement in your program. No other statements can precede it (except for comment lines started with an [[Apostrophe|apostrophe]] or [[REM]]). | ||
* Do not use [[OPTION _EXPLICIT]] in [[$INCLUDE]]d modules. | * Do not use [[OPTION _EXPLICIT]] in [[$INCLUDE]]d modules. | ||
| Line 34: | Line 33: | ||
{{PageSeeAlso}} | {{PageSeeAlso}} | ||
* [https://qb64phoenix.com/forum/showthread.php?tid=1727 Featured in our "Keyword of the Day" series] | |||
* [[OPTION _EXPLICITARRAY]] | * [[OPTION _EXPLICITARRAY]] | ||
* [[DIM]], [[REDIM]] | * [[DIM]], [[REDIM]] | ||
Latest revision as of 15:19, 25 September 2024
OPTION _EXPLICIT instructs the compiler to require variable declaration with DIM, REDIM or an equivalent statement.
Syntax
Description
- With OPTION _EXPLICIT you can avoid typos by having QB64 immediately warn in the Status area of new variables used without previous declaration.
- The use of OPTION _EXPLICIT does also enforce the requirement to DIM or REDIM any arrays before first use, no extra OPTION _EXPLICITARRAY is needed.
- Enable OPTION _EXPLICIT temporarily even if a program source file doesn't contain the directive by specifying the -e switch when compiling via command line (qb64 -c file.bas -e).
Errors
- If used, OPTION _EXPLICIT must be the very first statement in your program. No other statements can precede it (except for comment lines started with an apostrophe or REM).
- Do not use OPTION _EXPLICIT in $INCLUDEd modules.
Examples
Example: Avoiding simple typos with OPTION _EXPLICIT results shown in the QB64 IDE Status area.
OPTION _EXPLICIT DIM myVariable AS INTEGER myVariable = 5 PRINT myVariabe |
QB64 IDE Status will show: Variable 'myVariabe' (SINGLE) not defined on line 4
See also