Source code in the basic programming language

' Assertions
answer = assertion(42)
PRINT "The ultimate answer is indeed ", answer

PRINT "Now, expect a failure, unless NDEBUG defined at compile time"
answer = assertion(41)
PRINT answer
END

' Ensure the given number is the ultimate answer
FUNCTION assertion(NUMBER i)

    ' BaCon can easily be intimately integrated with C
    USEH
        #include <assert.h>
    END USEH

    ' If the given expression is not true, abort the program
    USEC
        assert(i == 42);
    END USEC

    RETURN i
END FUNCTION


subroutine assert (condition, message)
 if not condition then print "ASSERTION FAIED: ";message: throwerror 1
end subroutine

call assert(1+1=2, "but I don't expect this assertion to fail"): rem Does not throw an error
rem call assert(1+1=3, "and rightly so"): rem Throws an error

      PROCassert(a% = 42)
      END
      
      DEF PROCassert(bool%)
      IF NOT bool% THEN ERROR 100, "Assertion failed"
      ENDPROC