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The $CHECKING metacommand turns C++ event checking ON or OFF.




  • The Metacommand does not require a comment or REM before it. There is no space after the colon.
  • The OFF action turns event checking off and should only be used when running stable, errorless code.
  • The default $CHECKING:ON action is only required when checking has been turned OFF previously.
  • When $CHECKING:OFF is used, all error code and the reporting code is removed from the EXE program.
  • Warning: Turning OFF error checking could create a General Protection Fault (or segfault). Use only with 100% stable sections of code.


  • After every QB64 command is translated to C++, the compiler adds special code sections to check for ON TIMER (n) events and errors that may have occured in the last function call. Disabling error checking with the $CHECKING:OFF directive prevents the compiler from adding the extra code sections.
  • Setting $CHECKING:OFF is only designed for 100% stable, errorless sections of code, where every CPU cycle saved counts, such as in a software 3D texture mapper, for example.

See also

Keyword Reference - Alphabetical
Keyword Reference - By Usage
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