I want to store a letter into a variable so that whenever the program starts again it can use the variable in further program execution.
What is the way to achieve t
No, you cannot achieve this using variables. variables only exist untill the program finishes execution. Once the program is finished, no variable is retained.
You need to make use of file i/o. You can write the end (final) data of one execution to a file, the next time program runs, it can read the file contains and resume the exection.
For your reference,
In C
you can check below library functions
and their families.
In C++