In Clapp 202 there is a copy of The C programming Language book by Brian W. Kernighan and Dennis M. Ritchie, (K-R).
It is the best book to learn C!

From Chapter 1 do the following three exercises.

• K-R 1.9. Write a program that copies its input to its output replacing
  each string of one or more blanks by a single blank.
• K-R 1.14. Write a program to print a histogram of the frequencies of different characters in its input.
  Consider only numeric and alphabetic characters, and treat upper or lower case characters as equivalent.
  Print two tables of the results: one for the digits and one for the letters.
  To obtain proper alignment consider Allegra's post on Moodle.
• K-R 1.19. Write a function reverse that reverses the character string s.
  Use it to write a program that reverses its input a line at a time.

For the three programs read characters from the standard input and print the results to standard output.
To simulate an end-of-file (EOF) do Ctrl-D.

Reading through K-R Chapter 1 and exploring the snippet codes is essential.
Check my last post on Moodle News Forum.