| Description |
The $IOChecks compiler directive determines whether an exception is thrown when an IO operation encounters an error.
{$IOChecks On} default generates the EInOutError exception when an error occurs.
{$IOChecks Off} does not generate an exception. Instead, it is the responsiblity of the program to check the IO operation by using the IOResult routine.
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| Notes |
The IOResult routine resets the IO error value to 0 when called.
$IOChecks is equivalent to $I.
This directive can be used multiple times within your code.
The default value is $IOChecks On
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| Related commands |
| $I |
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Allows code in an include file to be incorporated into a Unit |
| IOResult |
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Holds the return code of the last I/O operation |
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| Example code : Try to create a directory twice |
// Full Unit code.
// -----------------------------------------------------------
// You must store this code in a unit called Unit1 with a form
// called Form1 that has an OnCreate event called FormCreate.
unit Unit1;
interface
uses
Forms, Dialogs;
type
TForm1 = class(TForm)
procedure FormCreate(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm} // Include form definitions
procedure TForm1.FormCreate(Sender: TObject);
var
error : Integer;
begin
// Try to create a new subdirectory in the current directory
// Switch off I/O error checking
{$IOChecks off}
MkDir('TempDirectory');
// Did the directory get created OK?
error := IOResult;
if error = 0
then ShowMessage('Directory created OK')
else ShowMessageFmt('Directory creation failed with error %d',[error]);
// Try to create the directory again - this will fail!
MkDir('TempDirectory');
error := IOResult;
if error = 0
then ShowMessage('Directory created OK again')
else ShowMessageFmt('Repeat creation failed with error %d',[error]);
// Delete the directory to tidy up
RmDir('TempDirectory');
// Switch IO checking back on
{$IOChecks on}
end;
end.
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| Hide full unit code |
Directory created OK
Repeat creation failed with error 183
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