I want to write a code for evaluating average result of exam marks. In my program, I want to include one function which will repeatedly ask for the correct range of marks defined by the principles rather the impossible. In this case, marks mustn't be smaller than zero or greater than 100. However if a user types a character accidentally, the code will keep on going. That is why I try to fix mine to actively respond when a letter or whatever is entered. But, the looping is somewhere at one point must be wrong, since I keep getting the result of infinite loop. That is why I am here asking for some help in guiding me. Thank you so much for your help. I use C language.