zlog is a reliable, high-performance, thread safe, flexible, clear-model, pure C logging library. Actually, in the C world there was NO good logging library for applications like logback in java or log4cxx in c++. Using printf can work, but can not be redirected or reformatted easily. syslog is slow and is designed for system use. So I wrote zlog. It is faster, safer and more powerful than log4c. So it can be widely used.