http://www.delphibbs.com/delphibbs/DispQ.asp?LID=3685176


2007-4-6 19:25:51 如要返回字符串要用PChar，最好用PChar用out或var方式返回，PChar的内存分配和释放在调用函数处理：GetMem(p, Size); FreeMem(p);

而在被调用函数写的方式应该是:


procedure GetStr(var Pstr: PChar);
var
str: string
begin
str := 'return string';
strCopy(PStr, PChar(str));
end;

调用函数写法:
TGetStr= procedure(var Pstr: PChar);

funtion GetDllStr: string
var
DllHnd: THandle;
GetStr: TGetStr;
Str: PChar;
strPath: string;
begin
AHaveWhere := 0;
DllHnd := LoadLibrary(PChar('testdll'));
try
if (DllHnd <> 0) then
begin
@GetStr :=GetProcAddress(DllHnd, 'GetStr');
if (@GetStr<>nil) then
begin
GetMem(Str, 1024);
try
GetStr(Filter);
result := StrPas(Filter);
finally
FreeMem(Str);
end;
end
else
begin
application.MessageBox(PChar('DLL加载出错，DLL可能不存在！'), PChar('错误'),
MB_ICONWARNING or MB_OK);
end;
end;
finally
FreeLibrary(DllHnd);
end;