$Q: Overflow Checking Switch


   $Q:  Overflow Checking Switch

Controls the generation of overflow checking code.

   Syntax:        {$Q+} or {$Q-}
   Default:       {$Q-}
   Type:          Local
   Menu Command:  Options|Compiler|Overflow checking

The $Q+ State

In the $Q+ state, certain integer operations are checked for overflow, such as:

      +, -, * Abs, Sqr, Succ, and Pred

The code for each of these arithmetic operations is followed by additional code that verifies that the result is within the supported range.

If an overflow check fails, the program terminates and displays a run-time error message.

Note that {$Q} does not affect the Inc and Dec standard procedures. These procedures are never checked for overflow.

The $Q switch is usually used in conjunction with the $R switch.

Enabling overflow checking slows down your program and makes it larger, so use {$Q+} only for debugging.

 The $Q- State

In the $Q- State, no overflow checking is done.

See Also


Тэги: $Q
| G+
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