PLEASE EXPLAIN ALSO THE CODE BESIDE IT BY COMMENTING

4. Write a C code to insert a character to a particular position in a string without using any standard library functions. The target character and position will be provided as inputs. (For example if the string is "Ana" and the target character and position are ' n ' and three, respectively, then the code must print "Anna" as output.) 5. Write a C code to check whether a string is a substring of another. The two strings are given as inputs. (The string "nana" is a substring of the string "banana")