Enter all sorts of data as char and convert it without errors!!

Have you ever asked the user to enter a number and then a letter is entered that ruins the program? Well here is the solution and explanation to solve this problem. This tutorial will explain how to use a specific function that will allow you to enter 1) positive numbers only 2) negative/positive numbers only 3) regular text 4) characters passwords 5) number passwords The tutorial also contains explanations for converting arrays of chars to integers and integers to arrays of chars without using the atoi and those basic functions. Enjoy! Dario