Dual validation with a do-while loop and if-else statement - c++

Question

I need to figure out how to validate 2 conditions.
Check if a previous number has been played.
Check if the number is between 1 and 9.
In either case, it should loop back to the beginning. With the first situation, it shouldn't run till the user enters a number that hasnt been played.
do
{
cout << "Interesting move, What is your next choice?: ";
cin >> play;
Pused[1] = play;
if(play != Pused[0] && play != cantuse[0] && play != cantuse[1] )
{
switch(play)
{
default:
cout << "Your choice is incorrect\n\n";
break;
}
}
}while(play != 1 && play != 2 && play != 3 && play != 4
&& play != 5 && play != 6 && play != 7 && play != 8 && play != 9);
Dis_board(board);

Answer 1

Instead of do-while loops, i like to use the combination of infinite loops + break statements, like this:
cout << "What is your first choice? ";
while (true)
{
// Input the choice, including validation
// Do the move
if (game_over)
break;
cout << "Interesting move; what is your next choice? ";
}
In the code above, the two comments represent code, which may itself contain loops. In order to reduce confusion, you might want to stuff this code into a separate function. For example, to input the choice:
while (true)
{
cin >> play;
bool is_illegal =
play == cantuse[0] ||
play == cantuse[1] ||
play < 1 ||
play > 9;
if (is_llegal)
cout << "Your choice is incorrect; please enter again: ";
else
break;
}
Note: to implement good handling of user errors, you also have to account for the case when the user enters nonsense instead of a number; look up istream::ignore and ios::clear for that.