OPTION EXPLICIT

OPTION _EXPLICIT instructs the compiler to require variable declaration with DIM, REDIM or an equivalent statement.

Syntax

OPTION _EXPLICIT

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

• Featured in our "Keyword of the Day" series
• OPTION _EXPLICITARRAY
• DIM, REDIM
• SHARED
• STATIC

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