Converting ZIP to 7z
If you want to convert the ZIP archive to 7z read this article.
Aspose.ZIP API provides the SevenZipArchive class to work with 7z archives. We can extract an entry to memory without saving it into intermediate storage and pass it into the 7z archive right away.
Transfer an Entry
The following code example demonstrates how to extract entries from the ZIP archive and immediately put them to the 7z archive. 7z entries will be compressed with the LZMA2 method regardless of what algorithm they had in the source archive. Entries that are directories are skipped, but their files are added respecting relative paths.