About getchar() function / scanf() function

do {
    printf("Enter a pair of integers:\n");
    scanf("%d %d", &evil1, &evil2);
    printf("The lesser of %d and %d is %d.\n", evil1, evil2, (evil1 < evil2) ? evil1 : evil2);
    printf("Press 'y' to continue,or 'q'to quit.");
    while((ch = getchar()) == '\n'); // I don't understand...


} } while (ch == 'y');
printf("Bye.\n");
return 0;