Define arrays. Explain review of arrays ?

Write a function that takes in the radius as input and returns the circumference of a circle.

Input a string from the user. Create a new string called ‘result’ in which you will replace the letter ‘e’ in the original string with letter ‘i’. 

Example : 

original = “eabcdef’ ; result = “iabcdif”

Original = “xyz” ; result = “xyz”

Brief about Bus structure. Explain types of Bus structures ?