In general, the flow of control can be altered in two ways: selective or iterative. Selective statements provide selection around a number of statements whereas iterative statements provide repetition of a group of statements until a certain condition is met. The idea behind repetition is to minimize the program code by putting those statements that are expected to repeat in a certain block and restrict it by a certain condition. C programming language provides three types of iterative statements: for, while, and do-while. For loop and while loop are pre-conditional looping mechanisms whereas do-while loop is a post-conditional one. Pre- conditional loops simply check the condition for repetition at the beginning of the block whereas post-conditional loops give first iteration to unconditionally execute and then check the condition for repetition at the end of the loop. a) Write a C program that prints values between user-specified lower and upper limits using a loop. The program should ask the limits first and then print from the lower to the upper. v What if the user enters the upper limit before the lower? Improve your solution! b) Write a C program that keeps asking the user to specify integer values for calculating the summation of all values until a zero value is entered? Zero is chosen as a dummy value for stopping the input! v Which looping strategy do you prefer? While or do-while? c) Write a C program that calculates the summation of digits of a user-specified three-digit number. For instance, if user's input was 123, then it would result 6, i.e. 1+2+3. d) Write a C program that prints the following using a double-for-loop. 1 3 5 7 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 v Try to replace for loops with do-while loops!