如何在使用结构的同时将字符串从数组传递到指针（在c中）

The point of this code is to read a string from the user (which is less than 50 characters) and then use the letters function to put the letters of the string in a pointer in such a way that each letter is going only once and then also counting the occurrence of each letter. Finally, with the use of report function it should output in the screen everything I just explained. For example, the user enters "Hello" the program outputs:The point of this code is to read a string from