C++ Average grade Calculation Error

[w0ot]

Hi all, i have this codes, but i came across some problem. let say i input 4 modules. and i have like A,A,F,F. by right the ans should be (4+4+0+0)/4 = 2
But program output my ans as 4.
Anyone can help me check where is the error and replace the error with the correct one ?

#include "stdafx.h"
#include <iostream>
#include <string>

using namespace std;

int main()
{
	char name [100];
    int n, ta, tb, tc, td, tf;
    ta=tb=tc=td=tf=0;

    char array[100];
	string s;

	cout <<"This is an Average Point Calculator. Just put in your 1-5 modules grade"<< endl;
	cout<<"What is your name?"<< endl;
	cin.getline (name,100);
	cout<<"Hello, " << name << "."<< endl;
    cout << "How many modules total ? ";
    cin >> n;

    for(int i=1; i<=n; i++)
    {
        do
        {
            cout << "Enter Module" << i << "'s grade in LETTER : ";
            cin >> s;
			if(s.length()>1)
				break;
			else array[i] = s[0];
			if(isalpha(array[i]))
            {
                if(tolower(array[i])=='a'){ ta++; break; }

                if(tolower(array[i])=='b'){ tb++; break; }

                if(tolower(array[i])=='c'){ tc++; break; }

                if(tolower(array[i])=='d'){ td++; break; }

                if(tolower(array[i])=='f') break;
            }
        } while(1);
    }
    cout << "Average grade of " << n << " subjects is : "  << (ta*4+tb*3+tc*2+td)*1.0/(ta+tb+tc+td+tf) <<endl;
}

[helios]

You're never incrementing tf, but you're including it as your divisor when printing.
Wouldn't it be easier to just divide by n, anyway?

[w0ot]

thanks helios. got it.