HOW TO THIS QUESTION IN C$++$

Hector is in grade $3$ and likes a girl in his class, Julia, very much. He has written a letter to her, but he needs you to help him to encode the letter, so that if someone in the class gets hold of it$,$ they would not be able to understand it$.$ Write a program that reads an input file with the letter character by character. Change the following characters:

t $($or T$)$ gets changed to $1$Y h $($or H$)$ gets changed to $1$O j $($or J$)$ gets changed to $1$X d $($or D$)$ gets changed to $1$B a $($or A$)$ gets changed to $1$S p $($or P$)$ gets changed to $1$M I $($or I$)$ gets changed to $1$Q

The rest of the characters remain the same. Read the file character by character, and write the character $($if it stays the same$)$ to the output file, or write the changed version to the output file. Call your output file encode.txt$.$

Create an input file called letter.txt with Hector$$s letter:

Dear Julia,

You are the most beautiful girl that I have ever seen. I was wondering if you would like to come and visit me$.$ My mother will make us pancakes with ice cream. My dog, Bella, just had three beautiful puppies. Mom says I may only keep one of them. I would like you to help me choose one, because they are all so cute and adorable. And just because you are my special friend, you may also have one if you want.

Your friend, Hector.