main.cpp

#include"Tekst.h"

int main()
{
	Tekst T("test2");
	T.Analyze();
	T.Sort();
	T.Save();
	system("pause");
	return 0;
}

Tekst.cpp

#include "Tekst.h"
Tekst::Tekst(std::wstring name):name_of_file(name)
{
	wchar_t z = 'a';
	for (int i = 0; i < size; i++, z++)
	{
		Litera.first = z;
		Litera.second = 0;
		Alfabet.push_back(Litera);
	}
}
Tekst::~Tekst()
{

}
void Tekst::Analyze()
{
	ifstream file;
	file.imbue(locale("Polish_poland.852"));
	wstring namefile = name_of_file + ".txt";
	file.open(namefile.c_str());
	if (!file.is_open())
	{
		cout << "Nie udalo sie otworzyc pliku o nazwie: " << name_of_file << endl;
		system("pause");
		exit(EXIT_FAILURE);
	}
	wchar_t znak;
	while (file >> znak)
	{
		if (isalpha(znak))
		{
			znak = tolower(znak);
			Alfabet[znak - 97].second++;
		}
	}
}
void Tekst::Sort()
{
	sort(Alfabet.begin(), Alfabet.end(),Compare);
}
void Tekst::Show()
{
	for (auto i : Alfabet)
		cout << i.first << " " << i.second << endl;
}
void Tekst::Save()
{
	ofstream file;
	string name = name_of_file + " - analiza.txt";
	file.open(name.c_str());
	if (!file.is_open())
	{
		cout << "Nie udalo sie otworzyc pliku o nazwie: " << name_of_file << endl;
		cout << "Byla to proba zapisu do pliku" << endl;
		system("pause");
		exit(EXIT_FAILURE);
	}
	for (auto i : Alfabet)
	{
		file << i.first << " " << i.second << endl;
	}
}

Tekst.h

#pragma once
#include<iostream>
#include<fstream>
#include<string>
#include<cctype>
#include<utility>
#include<vector>
#include<algorithm>
#include<locale>
using namespace std;
class Tekst
{
	wstring name_of_file;
	enum 
	{
		size = 26
	};
	struct compare
	{
		bool operator()(pair<wchar_t, int> a, pair<wchar_t, int> b)
		{
			return a.second > b.second;
		}
	}Compare;
	pair<wchar_t, int> Litera;
	vector<pair<wchar_t, int>> Alfabet;
public:
	Tekst() {};
	Tekst(wstring name);
	~Tekst();
	void Analyze();
	void Sort();
	void Show();
	void Save();
};