Get the first free drive letter

I am trying with code:

Var FirstFreeLetter

${For} $0 A Z

	IfFileExists $0\*.* 0 Done

	StrCpy $FirstFreeLetter $0

	${ExitFor}

	Done:

${Next}

but not success.

Thanks.

Have you tried one wildcard instead of *.*?

The drive root is a bit special, there is no ".." directory.

"\*" detects directory and/or root.

"\?" detects directory but not root?

"\." detects something but I don't remember what exactly.

var /global comspec
ExpandEnvStrings $comspec "%COMSPEC%"
nsexec::exectostack '"$comspec" /C wmic logicaldisk get size,freespace,caption'
Pop $0
Pop $0
${WordFind} "$0" "$\n" "*" $1
${For} $2 1 $1
${WordFind} "$0" "$\n" "+$2" $3
${WordFind} "$3" ":" "+1}" $4
${if} $3 != $4
${WordFind} "$3" " " "+1" $4
${WordFind} "$3" " " "+2" $5
${WordFind} "$3" " " "+3" $6
Math::Script 'r7 = f((r6=r6/1048576)-(r5=r5/1048576))'
Strcmp $7 0 +2
detailprint "Drive $4 Total:$6MB Free:$5MB Used:$7MB"
${endif}
${Next}

OK. Now it's working.

StrCpy $0 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

StrCpy $1 0

start:

StrCpy $2 $0 1 $1

StrCmp $2 '' end

IntOp $1 $1 + 1

;MessageBox MB_OK '$$0={$0}$\n$$1={$1}$\n$$2={$2}'

${If} ${FileExists} '$2:\*'

Goto start

${Else}

StrCpy $0 '$2:'

Goto end

${EndIf}

end:

MessageBox MB_OK|MB_USERICON '$0'