I have a text file that I want to compress after it gets an specified size. I\'ve already seen GZipStream
which works great, but RAR compression is much better.
As the RAR compression algorithm isn't free (only the decompression algorithm is), you won't find a library for it (or have to purchase a license).
A good alternative is the LZMA SDK that delivers the compression algorithms used in 7-Zip.
For a compression ratio/speed comparison, you can have a look e.g. at the Maximum Compression summary page, ranks 50 and 52, comparing WinRAR 4.01 in "Best Solid" mode and 7-Zip 9.22 in "Ultra" mode. WinRAR compresses only slightly better (<1%) and faster, 7-Zip decompresses faster.
Note that, as peachykeen noted, if you look at the efficiency ratings instead of size, WinRAR in normal mode is much faster than 7-Zip.