function TGenFuncUtils.GetEnvironment(const EnvVar,default : string) : string; var EnvList, Value, Name : PChar; EnvName : string; SignPos : integer; found : boolean;
begin EnvList := GetEnvironmentStrings;
This code neglects to call FreeEnvironmentStrings when it's finished with the list.
found := false;
while EnvList^ <> #0 do begin EnvName := StrPas(EnvList);
The StrPas function is never needed. You can assign EnvList directly to EnvName and get the same result.
SignPos := pos('=',EnvName); EnvName := copy(Envname,1,SignPos-1); // truncate Envname to remove value if EnvName = EnvVar then begin Name := StrAlloc(255); //allocate memory for name variable Value := StrAlloc(255); // allocate memory for value variable
StrPCopy(Name,EnvName); // copy string value 'EnvName' to PChar Name GetEnvironmentVariable(Name, Value, 255); found := true; Result := StrPas(Value); //convert value to string and assign to Result
StrDispose(Name); StrDispose(Value); break; end; Inc(EnvList, StrLen(EnvList)+1); end;
if not(found) then begin MessageDlg('Cannot Find Environment Variable'+#10#13+#10#13+'Continuing with default values',mtinformation,[mbOk],0); Result := default; end; end;
The entire loop is pointless. The code can be written much more simply. The code below takes advantage of the return value of GetEnvironmentVariable, which indicates whether the requested variable exists. It also doesn't assume that the environment variable's value will fit in the rather arbitrary 255-byte limit of your code. Values may be as large as 32767 characters. (The code also fixes the order of the #13 and #10 characters in the error message; carriage return comes _before_ line feed.) The function will raise an EWin32Error exception in two circumstances:
1. If the API function fails while determining the required buffer size for any reason other than the variable name not existing
2. If the second call to the API function returns something other than what the first call said it should return (if the variable's value changed mid-call, for instance, which could happen in a multi-threaded program)
function GetEnvironment(const EnvVar, Default: string): string;
var
Len: DWord;
begin
Len := GetEnvironmentVariable(PChar(EnvVar), nil, Len);
if Len = 0 then begin
if GetLastError <> Error_EnvVar_Not_Found then RaiseLastOSError;
MessageDlg('Cannot Find Environment Variable'#13#10#13#10
+ 'Continuing with default values', mtInformation, [mbOK], 0);
Result := Default;
exit;
end;
SetLength(Result, Pred(Len));
Len := GetEnvironmentVariable(PChar(EnvVar), PChar(Result), Len);
Win32Check(Len = Length(Result));
end;You might even just want to call the GetEnvironmentVariable function from the SysUtils unit. If the requested variable doesn't exist, then the SysUtils function returns the empty string.
-- Rob
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