Digital filter library in C/C++?

Question

C++ / C#

I am looking for a library in C or C++ that will allow me to easily (and most importantly correctly) filter the flow of measurements. Interested in butterworth low-pass, high-pass and notch , while frequencies and dimensions should be set by parameters (and not compiled into a program)

Answer 1

https://github.com/vinniefalco/DSPFilters ?