Programming :: How Does Cin Work?

This code will execute fairly well, however, if you enter multiple values that are not A/a or b, 1 or 2, then when the program resets, cin does not behave normally. Instead of waiting for input, it acts as if it has already been given input, and the input is the next character from the one entered.For example, entering "345" and submitting it at the (cin >> a line will individually pass the values 3, 4, and 5 through the if/else and switch statements, rather than only inputting the first value, 3, or all the values, 345.

If you enter, for example, "3343634563456345", then it will pass through the do{}while(); loop 16 times, with each pass having a = to the next character value. The cin >> a; is performed, and this is verifiable in GDB, however it never asks for input from stdin, and instead gets its input from somewhere else. How can I observe that, and what is going on?Furthermore, if you enter "cdefghijklmnopqrstuvwxyzab", it will pass through 25 times, and stop at a, which goes through the switch, and ends at a case statement that does not adjust the false value of mreset, thereby allowing the program to end.