Please solve all the questions

(c programming)

1. What are the advantages of using a function in a program? 2. Explain the following concepts with respect to functions. a) Function prototype. b) Function definition. c) Function call. d) Local variables. 3. List the types of user-defined functions. 4. Write a complete C program using array with function. As such, the function, findLetter, that receives a string, str, and a character, ch, as arguments and returns the position of the first occurrence of ch in str or 1 if ch doesn't exist in str. Use the proposed names for the arguments. Demonstrate the use of your function by calling it from a main function. After calling your function, findLetter, print the character entered by the user and its position within the string. If the character is not found within the string, then print the character is not found