C programming

4. What is the NOT principle? Why is it important?

6. List the advantages and disadvantages of cohesive functions.

7. If given the choice between writing your own function or using a library function, can you think of situations where it would be preferable to write your own?

12. A light year is a unit of astronomical distance that measures how far light can travel in one year, defined as 365.25 days, which is about 9.4507 x 1012, or about 5.878 trillion miles. A parsec is a unit of astronomical distance, equal to about 3.26 light years. One parsec corresponds to the distance at which the mean radius of the earth's orbit subtends an angle of one second of arc. Since the numbers grow so large so quickly, it's often easier for astronomers to work with parsecs, and convert them back to light years, or even miles, when needed. Write a function to convert parsecs to light years.