سلام این رو تو button بنویس
filename = "";
saveFileDialog1.Filter = "(*.text)|*.text";
saveFileDialog1.Title = "select filename for save";
saveFileDialog1.FileName = filename;
saveFileDialog1.ShowDialog();
filename = saveFileDialog1.FileName;
if (filename != "")
{
FileStream tex = newFileStream(filename, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.ReadWrite);
BinaryWriter binarytex = newBinaryWriter(tex);
binarytex.Write(TextBox1.text);
tex.Close();
binarytex.Close();
}
راستی اینم هام یادت نره
privateFileStream input;
privateBinaryReader reader;
System.String filename;