FileToGrid (Delphi)
Description
The following example uses a button, a string grid, and an Open dialog box on a form. When the button is clicked, you for a file name. When you click OK, the specified file is opened, read into a buffer, and closed. Then the buffer is displayed in two columns of the string grid. The first column contains the character values in the buffer. The second column contains the numeric values of the characters in the buffer.
Code
// Read File to Grid
procedure TForm1.Button1Click(Sender: TObject);
var
iFileHandle: Integer;
iFileLength: Integer;
iBytesRead: Integer;
Buffer: PAnsiChar;
X, Y, I: Integer;
StringLen, colcnt, rowcnt: Integer;
cellString: String;
begin
if OpenDialog1.Execute then
begin
try
iFileHandle := SysUtils.FileOpen(OpenDialog1.FileName, fmOpenRead);
iFileLength := SysUtils.FileSeek(iFileHandle,0,2);
FileSeek(iFileHandle,0,0);
// Buffer := PChar(System.AllocMem(iFileLength + 1));
// iBytesRead := SysUtils.FileRead(iFileHandle, Buffer^, iFileLength);
// FileClose(iFileHandle);
// iFileHandle := SysUtils.FileOpen(OpenDialog1.FileName, fmOpenRead);
// iFileLength := SysUtils.FileSeek(iFileHandle,0,2);
// FileSeek(iFileHandle,0,0);
colcnt := StringGrid1.ColCount;
iBytesRead := SysUtils.FileRead(
iFileHandle,
colcnt,
4); // 4 because it's an integer
rowcnt := StringGrid1.RowCount;
iBytesRead := SysUtils.FileRead(
iFileHandle,
rowcnt,
4); // 4, because it is an integer.
for X := 0 to StringGrid1.ColCount - 1 do
begin
for Y := 0 to StringGrid1.RowCount - 1 do
begin
try
iBytesRead := SysUtils.FileRead(iFileHandle, StringLen, 4); // 4 because it's an integer
Buffer := System.AllocMem(StringLen + 1);
// GetMem(Buffer, StringLen); { allocate the buffer }
iBytesRead := SysUtils.FileRead(iFileHandle, Buffer^, StringLen);
// for I := 1 to StringLen do
// cellString[I] := Buffer[I - 1];
StringGrid1.Cells[X,Y] := AnsiString(Buffer);
finally
FreeMem(Buffer);
end;
end;
end;
finally
FileClose(iFileHandle);
end;
end;
end;
// Write Grid into File.
procedure TForm1.Button2Click(Sender: TObject);
var
BackupName: string;
FileHandle: Integer;
StringLen: Integer;
X, Y, I: Integer;
colCountLength, rowCountLength: Integer;
Buffer: PAnsiChar;
cellString: AnsiString;
begin
if SaveDialog1.Execute then
begin
if FileExists(SaveDialog1.FileName) then
begin
BackupName := SysUtils.ExtractFileName(SaveDialog1.FileName);
BackupName := ChangeFileExt(BackupName, '.BAK');
//Removing previously created .BAK files, if found.
if FileExists(BackupName) then
begin
DeleteFile(BackupName);
end;
if not RenameFile(SaveDialog1.FileName, BackupName) then
raise Exception.Create('Unable to create backup file.');
end;
FileHandle := FileCreate(SaveDialog1.FileName);
{ Write out the number of rows and columns in the grid. }
colCountLength := SizeOf(StringGrid1.ColCount);
FileWrite(FileHandle,
PAnsiChar(StringGrid1.ColCount), colCountLength);
rowCountLength := SizeOf(StringGrid1.RowCount);
FileWrite(FileHandle,
PAnsiChar(StringGrid1.RowCount), rowCountLength);
for X := 0 to StringGrid1.ColCount - 1 do
begin
for Y := 0 to StringGrid1.RowCount - 1 do
begin
try
{ Write out the length of each string, followed by the string itself. }
StringLen := Length(StringGrid1.Cells[X,Y]);
FileWrite(FileHandle, PChar(StringLen), SizeOf(StringLen));
GetMem(Buffer, StringLen); { Allocate the buffer. }
cellString := StringGrid1.Cells[X,Y];
for I := 1 to StringLen do
Buffer[I - 1] := cellString[I];
FileWrite(FileHandle, Buffer^, StringLen);
finally
FreeMem(Buffer, StringLen);
end;
end;
end;
FileClose(FileHandle);
end;
end;
Uses
- System.SysUtils.FileExists ( fr | de | ja )
- System.SysUtils.FileOpen ( fr | de | ja )
- System.SysUtils.FileSeek ( fr | de | ja )
- System.SysUtils.FileRead ( fr | de | ja )
- System.SysUtils.FileWrite ( fr | de | ja )
- System.SysUtils.FileClose ( fr | de | ja )