File code converter source code

Recently I was working on a project using VS2005, and I encountered a project in which there were many files whose encoding was not uniform. Some were UTF-8, and some were GB32. When publishing the website, it was a mess. You can change them one by one through the "Advanced Save Options" in the VS environment. Because there are too many, dozens of them, and repeated work is very unpleasant, so I wrote this small program myself. Before writing, refer to the experience of netizens qing and Randy052.

Features:
1. Can support conversion between common encoding formats such as UTF-8, UTF-7, Unicod, ASCII, GB2312, and Big5.
2. Supports three file batch selection methods: folder batch selection, file multi-selection, and copying in the clipboard, which can achieve index conversion.
3. Support file filtering, using the file filtering method of openFileDialog.
4. Supports automatic identification of source file encoding, which can be used to unify the format of unknown files.
5. Support backup