Solutions for K & R Exercise 5-6

The following are pointer versions of previous exercises.

5-6A    Exercise 4-12 - functions: getline, atoi, and itoa
5-6B    Exercise 4-13 - functions: getline and reverse
5-6C    Exercise 4-1   - functions: getline and strindex
5-6D    Exercise 4-10 - functions: getline, getop, and ftoarray