Scanning character in a while loop - c

Question

char player_select(void){
char player = 'n';
while(player == 'n'){
printf("Select your player (X or O): ");
scanf("%c\n", &player);
if(player != 'X' && player != 'O'){
printf("Invalid input. Try again.\n");
player = 'n';
}
}
printf("Your character input is: %c\n", player);
exit(0);
return player;
}
I am getting some weird output here:
Select your player (X or O): X
Invalid input. Try again.
Select your player (X or O): i
Your character input is: X

Answer 1

Incorrect use of scanf()
// scanf("%c\n", &player);
scanf(" %c", &player);
The '\n' in "%c\n" does not do what you think. '\n' tells scanf() to consume white-space like '\n' and ' ' until non-white-space occurs. You input was not as described.
Since stdin is buffered, text by itself, will not typically get read until a '\n' follows.
It gets complicated to explain in detail why things failed. So briefly, use " %c" instead of "%c\n". Or better yet, use fgets().
buffer player[10];
fgets(ch, sizeof ch, stdin);
if(player[0] != 'X' && player[0] != 'O') { ...

Answer 2

I hope this will work for you.
I have removed the \n inside the scanf and i have added while(getchar()!='\n'); for emptying stdin.
char player_select(void){
char player = 'n';
while(player == 'n'){
printf("Select your player (X or O): ");
scanf("%c", &player);
if(player != 'X' && player != 'O'){
printf("Invalid input. Try again.\n");
player = 'n';
}
while(getchar()!='\n');
}
This is the output:
Select your player (X or O): A
Invalid input. Try again.
Select your player (X or O): X
Your character input is: X

Answer 3

Try:
if (scanf("%c\n", &player) == 1 && player != 'X' && player != 'O'){
printf("Invalid input. Try again.\n");
player = 'n';
}
Bring scanf into the if, removing from your above code, and check its return value == 1.
You can try removing the \n from scanf mask if this won't suffice.