[[OPTION _EXPLICIT]] instructs the compiler to require variable declaration with [[DIM]], [[REDIM]] or an equivalent statement.
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: [[OPTION _EXPLICIT]]
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* With [[OPTION _EXPLICIT]] you can avoid typos by having QB64 immediately warn in the '''Status area''' of new variables used without previous declaration.
* 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'').
* If used, [[OPTION _EXPLICIT]] must be the very first statement in your program. No other statements can precede it (except for [[$NOPREFIX]] or comment lines started with an [[Apostrophe|apostrophe]] or [[REM]]).