Retrieves the physical path that a virtual path, either absolute or relative, or an application-relative path maps to.
public string MapPath(
A String that represents the virtual path.
The MapPath property can potentially contain sensitive information about the hosting environment. The return value should not be displayed to users.
The following example uses the MapPath method to obtain the physical path of a subfolder. It then appends the file name that is read from the Text property of a TextBox control. The result is the absolute physical path to that file.
String fileNameString = this.MapPath(subFolder.Text);
fileNameString += "\\" + fileNameTextBox.Text;