DelphiBasics $OverFlowChecks Compiler Directive Determines whether Delphi checks integer and enum bounds

{$OverFlowChecks Off} 1 2  {$OverFlowChecks On}

Description The $OverFlowChecks compiler directive determines whether Delphi should add code to check for integer and enum operation value overflows.   This is set Off by default, meaning that a bad integer or enum operation will pass unnoticed, revealing itself in a difficult to debug part of the code.   It is recommended to switch on $OverFlowChecks in order to detect overflows before they cause problems. This will result in the raising of an exception, allowing code testing to correctlt identify the point of failure. Notes $OverFlowChecks is equivalent to $Q. It can and should only be set once in your code. The default value is $OverFlowChecks Off. Related commands $Q Determines whether Delphi checks integer and enum bounds  Download this web site as a Windows program.

Example code : Trapping overflow values var   myNumber : Byte; begin   // Set overflow checking on   {$OverFlowChecks On}   // A byte can hold numbers up to 255   myNumber := 255;   ShowMessage('myNumber = '+IntToStr(myNumber));   // But incrementing beyond 255 will throw an exception   Inc(myNumber);   ShowMessage('myNumber = '+IntToStr(myNumber)); end; Show full unit code   myNumber = 255      Delphi throws the EIntOverflow exception   Example code : Ignoring overflow values var   myNumber : Byte; begin   // Set overflow checking off   {$OverFlowChecks Off}   // A byte can hold numbers up to 255   myNumber := 255;   ShowMessage('myNumber = '+IntToStr(myNumber));   // But incrementing beyond 255 will wrap around to 0   Inc(myNumber);   ShowMessage('myNumber = '+IntToStr(myNumber)); end; Show full unit code   myNumber = 255   nyNumber = 0   Delphi Programming © Neil Moffatt . All rights reserved.  |  Home Page