How to delete a read-only file in C #

How to delete a read-only file in C #
Get the file version information:
Fileversioninfo myfileversioninfo1 = fileversioninfo. getversioninfo ("D: \ test. dll ");
Textbox1.text = "version:" + myfileversioninfo1.fileversion;
Modify file attributes and delete read-only files:
In the following example, you want to copy the E: \ test.txt file to D: \ TMP \ test.txt, but D: \ TMP \ test.txt already exists.
// File. Copy (sourcefile, destinationfile, true); used to copy an object
// When destinationfile already exists, you cannot copy file file1 to the target file,
// Delete the destination file first. The file. Delete () method cannot delete the read-only file,
// Therefore, if the file attribute is read-only (the attributes attribute contains "readonly "),
// First reset the file property to normal and then delete the file:
String file1 = "E: \ test.txt ";
String destinationfile = "D: \ TMP \ test.txt ";
If (file. exists (destinationfile ))
{
Fileinfo Fi = new fileinfo (destinationfile );
If (Fi. Attributes. tostring (). indexof ("readonly ")! =-1)
Fi. Attributes = fileattributes. normal;
File. Delete (destinationfile );
}
File. Copy (file1, destinationfile, true );