First, start by printing out a prompt for the user to input the string. Then, use fgets() in a while loop to read the user input line by line. Once we read in a string, we want to find any newline character also read in along the string, and replace it with a NUL character. If the user did not enter any string (simply pressed enter), then we want to immediately reprompt, and skip the search. Before performing the search, we also need to pre-process the string by lowercasing every character. Program in c