从文本文件中读取然后在程序中使用输入

I want to have a program read a text file with 20 single characters, that are on separate lines. I want to then have those characters compared against preprogrammed letters in the program where it will output the wrong ones and the total wrong. I have successfully constructed the program where I can manually enter the letters and it will do as I wanted, but my knowledge of using files within the code is limited. I have read about vectors but I would like to keep it simple first and get the hang of it before I try to learn something else. I have tried to set up a some code that resembles what I think it should probably look like. I want to have a program read a text file with