一个类型转换的问题

Question

var
    iFileHandle: Integer;
    iFileLength: Integer;
    ConnectionStrBuf:PChar;
..........
               ConnectionStrBuf:=PChar(AllocMem(iFileLength+1));
               FileRead(iFileHandle, ConnectionStrBuf^, iFileLength);
               FileClose(iFileHandle);
               SPSADOConnection.ConnectionString:= ConnectionStrBuf;               showmessage(SPSADOConnection.ConnectionString);//这里发现了只赋了一个字符
..........我想ConnectionStrBuf是PChar型,怎么才能把它的内容赋给一个widestring型?

Answer 1

var
  P: PChar;
  W: WideString;
  S: string;
begin
  S := 'PChar needs to be allocated memory before using it.'#13#10 +
       'You should call FreeMem to dispose its memory, too.';
  GetMem(P, 200);
  StrLCopy(P, @S[1], 200);
  W := P;
  ShowMessage(W);
  FreeMem(P);
end;

Answer 2

try
               GetMem(ConnectionStrBuf,iFileLength+1);
               FileRead(iFileHandle, ConnectionStrBuf^, iFileLength);
               FileClose(iFileHandle);
               ConnectionStrBuf[iFileLength]:=#0;
               SPSADOConnection.ConnectionString:= String(ConnectionStrBuf);
finally
  FreeMem(ConnectionStrBuf);
end;

Answer 3

GetMem(ConnectionStrBuf,iFileLength+1);
try
               FileRead(iFileHandle, ConnectionStrBuf^, iFileLength);
               FileClose(iFileHandle);
               ConnectionStrBuf[iFileLength]:=#0;
               SPSADOConnection.ConnectionString:= String(ConnectionStrBuf);
finally
  FreeMem(ConnectionStrBuf);
end;

Answer 4

to  Hillside(要命的是买不到D盘了): 还是不行,用messagebox打印connectionstrbuf里面的内容还是只有第一个字符

Answer 5

var
  iFileHandle: Integer;
  iFileLength: Integer;
  ConnectionStrBuf:WideString;
.....
  SetLength(ConnectionStrBuf,iFileLength);
  FileRead(iFileHandle, ConnectionStrBuf[1], iFileLength);
  FileClose(iFileHandle);
  SPSADOConnection.ConnectionString:= ConnectionStrBuf;
  ShowMessage(SPSADOConnection.ConnectionString);

Answer 6

你的代码中：
 SPSADOConnection.ConnectionString:= ConnectionStrBuf;
改为：
 SPSADOConnection.ConnectionString:=WideString(ConnectionStrBuf);
var
  ConnectionStrBuf:PChar;
改为：
  ConnectionStrBuf:PWideChar;

Answer 7

blazingfire(烈焰):谢谢您，问题解决了