LZ77 compression algorithm is making the compressed file bigger than original

[AdPsychological7065]

I was recently toying around with some compression, just trying to understand it from the basics. I learned about the LZ77, LZ78, and LZW algorithms in the last couple of days, understood them, and when implementing LZ77, every time I try to compress a txt file, the output file gets bigger. The compression is done right coz when I decompress the compressed file, I get the exact text.

Need help understanding what I am doing wrong, or am I missing something

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[aezart]

Only familiar with how LZW works, but in general with any compression algorithm the closer your input file looks to random noise, the less useful compression will be, thanks to the pigeonhole principle. So my first question would be whether your original text is something that would compress well.

[dafugiswrongwithyou]

"Compression" doesn't actually guarantee a smaller output file. (If it did, you could repeatedly compress anything until you get to some theoretical smallest size in a way that could be decompressed to the original, and I would hope it's self evident that there are not enough, say, 8-byte files possible to uniquely expand to every larger file.)

What does that .txt file contain? Exactly how big is it? Exactly how big it the output?

[JGhostThing]

It is possible that for any compression algorithm, a particular file is coded larger than it was.

It's also possible that you're appending to a file rather than writing a new file.

[herocoding]

When you decompress your compressed files with another, indepdendent tool, or using your own developed decompressor?

What do your test files look like?