#include <iostream>
#include <fstream>          // for ifstream
#include <cctype>           // for tolower(), isalpha()
#include <string>
using namespace std;

#include <iostream>
#include <vector>

// count # occurrences of all characters in a file
// written: 8/5/94, Owen Astrachan, modified 5/1/99
// modified by Albert Levi 8/14/2002 and 12/17/2007
// modified by Gulsen Demiroz 11/5/2009

void Print(const vector<int> & counts, int total);
vector<int> Count (istream & input, int & total);

int main()
{
    int         totalLetters = 0;              // counter for all letters      
	string filename;
	cout << "enter name of input file: ";
	cin >> filename;
	ifstream    input(filename);

    if (input.fail() )
    {   
        cout << "could not open file " << filename << endl;
		cin.get();
		cin.ignore();
        return 0;
    }

    // 0 for 'a', 1 for 'b', 2 for 'c', so on, 25 for 'z'
	// all initialized to 0
    vector<int> charCounts(26);  
	// vector<int> charCounts;
 
    charCounts = Count(input, totalLetters);
    Print(charCounts, totalLetters);
    
	cin.get();
	cin.ignore();
    return 0;
}

vector<int> Count (istream & input, int & total)
// precondition: input open for reading and file pos. 
//               pointer is at the beginning
//               counts[k] == 0, where 0 <= k and k < 26
// postcondition: counts[k] = # occurrences of letter: 
//                0th entry for 'a', 1st for 'b', so on
//                total = # alphabetic characters     
{
    char         ch;
	vector<int> counts(26, 0);

    while (input.get(ch))               // read a character
    {   
		if (isalpha(ch))                // is alphabetic (a-z) or (A-Z)?
        {
			total++;
            ch = tolower(ch);           // convert to lower case
            counts[ch - 'a']++;         // count all characters 
		}
	}

	return counts;
}

void Print(const vector<int> & counts, int total)
// precondition: total = total number of  letters
// postcondition: all values of counts from 'a' (0) to 'z' (25) printed     
{ 

    cout.setf(ios::fixed);     // print real numbers in decimal point notation
    cout.precision(1);         // print 1 decimal place 

    for(int k = 0; k <= 25; k++)
    {   
        cout << char(k+ 'a') << "\t" << counts[k] << "\t";
        cout << 100 * double(counts[k])/total << "% \n";
    }
}