From QB64 Wiki
Jump to navigation Jump to search

The _ASSERT statement can be used to perform tests in code that's in development, for debugging purposes.


_ASSERT condition[, errorMessage$]


  • condition is the condition that must be met in order to consider the _ASSERT valid.
  • Optional errorMessage$ is the message to be displayed in the console window if $ASSERTS:CONSOLE is used.
  • If the condition is not met (that is, if it evaluates to 0), an error occurs ("_ASSERT failed on line #") and program execution stops.


  • Version 1.4 and up.


Example: Adding test checks for parameter inputs in a function.

$ASSERTS:CONSOLE DO a = INT(RND * 10) b$ = myFunc$(a) PRINT a, , b$ _LIMIT 3 LOOP UNTIL _KEYHIT FUNCTION myFunc$ (value AS SINGLE) _ASSERT value > 0, "Value cannot be zero" _ASSERT value <= 10, "Value cannot exceed 10" IF value > 1 THEN plural$ = "s" myFunc$ = STRING$(value, "*") + STR$(value) + " star" + plural$ + " :-)" END FUNCTION

See also

Keyword Reference - Alphabetical
Keyword Reference - By Usage
Main Wiki Page