C library has many functions which are not used at all. I read libc documentation and found many useful functions which are not commonly used in day to day programming. If you find the document, do read it, to find some of interesting functions which makes programming simple.
If’s a big document, so not uploading here. I don’t have the link to online reference too. If any of you find a online reference, do send me a message, will provide the link over here.