Delphi in a Nutshell

Name

$OverflowChecks Compiler Directive

Syntax

{$Q-}                 // default
{$OverflowChecks Off} // default
{$Q+}
{$OverflowChecks On}

Scope

Local

Description

The $OverflowChecks directive tells the compiler to generate code that checks the result of integer and enumerated operations to ensure the results are within the bounds of the integer or enumerated type. If an operation produces an out-of-range result, Delphi reports runtime error 5 (EIntOverflow).

Tips and Tricks

You should always enable the $OverflowChecks directive because it can catch numerous errors in your code. A common misconception is that the checks should be disabled in released programs. If an integer or enumerated overflow occurs, you want to catch the error as soon as possible, and not wait for the error to propagate in unknown and unpredictable ways through your program, possibly corrupting your user’s data along the way. Do not disable the overflow checks unless you have a specific performance problem, and then disable the checks only in the performance-critical parts of your code.

See Also

$RangeChecks Compiler Directive