Using getchar() function - c++

Question

I used getchar() to stop the while string. My problem is that it does stop the while string if I type one or two characters, if the user input is more the two characters nothing happens.
here is the code:
printf("enter srting\n");
while ((tmp=getchar()) !='\n') { \\here is my problem
count_letters++;
/* COUNTING WORD THAT START WITH LETTES L,A,C,H */
while (count_letters%3==0) {
switch (tmp) {
case 'A': count_a++;
break;
case 'C': count_c++;
break;
case 'H': count_h++;
break;
case 'L': count_l++;
default:
break;
}
} /* end of count letters while */
n1=n2;
n2=n3;
n3=tmp;
if (n1=='H' && n2=='Y' && n3=='A') {
count_hya++;
}
} /* end of getchar while */
printf("\n");
printf("%d", count_letters);

Answer 1

I believe it's your code :
"while (count_letters%3==0))"
is something wrong!
because when you type more than three letters,your variable "count_letters" will add to 3 due to the code:"count_letters++;".
May be you could change the "while" to "if" and see if it's working correctly~

Answer 2

Here's the problem:
while (count_letters%3==0) {
switch (tmp) {
case 'A': count_a++;
break;
case 'C': count_c++;
break;
case 'H': count_h++;
break;
case 'L': count_l++;
default:
break;
}
}
when your the third character is read, your program enters a infinite loop because of (count_letters%3==0)
I can't understand the purpose of your code.
I suggest using gets() and string manipulation functions because you are processing an entire line. (see string.h)
getchar() is also less efficient compared with gets() + for-loop