Goto

goto is an unconditional jump to a previously declared label (either before or after the goto command). It is a reserved word.

Usage of goto in high-level programming languages such as Pascal is highly discredited, since control structures of all sorts are available.

The last situation a goto is agreed with bad grace to be a significant system error, where a “graceful exit” is better than causing a system breakdown.

As an example, here an excerpt from FPC’s code base rtl/inc/extres.inc]:

procedure InitResources;

label ExitErrMem, ExitErrFile, ExitNoErr;
begin

  ResHeader:=GetMem(sizeof(TExtHeader));
  if ResHeader=nil then goto ExitErrFile;

  goto ExitNoErr;

  ExitErrMem:
    FreeMem(ResHeader);
    ResHeader:=nil;
  ExitErrFile:
    {$I-}
    Close(fd);
    {$I+}
  ExitNoErr:
end;

According to the value of returnNilIfGrowHeapFails getMem possibly may return nil. Instead of placing everything in a “success”-branch, a couple goto instructions were chosen.

See also

• exit
• {$goto} compiler directive
• system.longJmp

From the Free Pascal wiki, page "Goto", as it stood on 2022-01-24 after a change by Kai Burghardt, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's Licensing page. If you have concerns about this material, message the admin.