filesystems - How to find out if a directory exists on Delphi XE2 *correctly*? -

i need check if directory exists! if directory "e:\test" e: cd/dvd drive , there no disk inserted on it, see following delphi , windows issues.

the first method:

function direxists(name: string): boolean; var   code: integer; begin   code := getfileattributesw(pchar(name));   result := (code <> -1) , (file_attribute_directory , code <> 0); end; 

it gives range check error. can't use {$rangechecks off}, {$rangechecks on} blocks because:

1. it breaks current state of $rangechecks option.
2. we see system error drive not ready instead range check error. need check if directory exists without error dialogs user.

the second method:

if directoryexists(name, true) ... 

this function returns true non-existing e:\test directory on empty cd/dvd drive. can't use because works incorrectly.

but then, how find out if directory exists?

p.s. think error exists cd/dvd drive. using windows 7 x64 on vmware fusion 5 under mac os x 10.8.4 external cd/dvd drive.

you can fix function doesn't cause range check errors:

function direxists(name: string): boolean; var   code: dword; begin   code := getfileattributes(pchar(name));   result := (code <> invalid_file_attributes)      , (file_attribute_directory , code <> 0); end; 

the range check errors due mixing signed , unsigned types. remy points out useful trick set compiler options , restore prevailing state. that's trick learn, don't need here.

the xe3 implementation of directoryexists modified address problem have encountered. so, if using xe3+ option, should take it.

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to suppress system error dialogs call @ process startup:

procedure setprocesserrormode; var   mode: dword; begin   mode := seterrormode(sem_failcriticalerrors);   seterrormode(mode or sem_failcriticalerrors); end; 

doing best practise described on msdn:

best practice applications call process- wide seterrormode function parameter of sem_ failcriticalerrors @ startup. prevent error mode dialogs hanging application.