Check this website for C programming language tutorial.
http://www.techcrashcourse.com/2016/02/c-programming-language-crash-course.html

Check this website http://www.techcrashcourse.com . It is very good for beginners. It contains tutorial and sample programs of c, c++, java, data structures etc with explanation and sample input output.

Here are some interesting facts about C programming language.

C language was originally developed by Dennis Ritchie between 1969 and 1973 at AT&T Bell Labs.
The UNIX Operating system was totally written in C programming language by 1973.
C Language was originally developed for creating system applications that direct interacts to the hardware devices.
B language is the precursor of C.
C is considered to be the mother of all today's modern programming languages.
http://www.techcrashcourse.com/2015/05/c-programming-language-introduction.html

We can find the power of a number without using pow function and using recursion.
Let power(a, b) means ab.
If b is even : power(a, b) = power(a, b/2)*power(a, b/2);
if b is odd : power(a, b) = power(a, b/2)*power(a, b/2)*a;
For example:
28 = 24 * 24;
29 = 24 * 24 * 2;
Source : http://www.techcrashcourse.com/2014/10/c-program-calculate-power-of-number.html