Add files and write portion that generates the compressed version of …

Compress.H

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+#ifndef __COMPRESS_H__
+#define __COMPRESS_H__
+
+#include "Huffman.H"
+
+using namespace std;
+
+class Compress : public Huffman{
+	int _counter; // Counts the number of bits used for compression (Needed for the header)
+
+	map<char,int> countLetters();
+	string generateHeader();	
+	string generateBody();
+public:
+
+	Compress(string fname) : Huffman(fname), _counter(0){}
+	~Compress(){}
+
+	void generateTree();
+	void compressFile(string outFile);
+
+};
+
+
+template <class Ptr>
+string preOrder(Ptr curr);
+
+#endif

Compress.cpp

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+#include "Compress.H"
+
+#include <fstream>
+#include <iostream>
+#include <vector>
+#include <map>
+#include <stdlib.h>
+
+using namespace std;
+
+map<char,int> Compress::countLetters(){
+    std::ifstream inpFile (_fname); //Will read the file
+    std::string line;
+	map<char,int> freq = map<char,int>();
+
+    if (inpFile.is_open()){
+        //This part will count the number of occurences
+        while(getline(inpFile,line)){
+            for (char c : line){
+                freq[c]++;
+            }
+        }
+		return freq;
+    }
+    else{
+        throw(std::string("[Error] Could not open file " + _fname + "  for countLetters() \n"));
+    }
+
+}
+
+void Compress::generateTree(){
+
+	map<char,int> freq = countLetters();
+    vector<shared_ptr<Node>> lst = vector<shared_ptr<Node>>(freq.size());
+
+    //Add the char and its frequency into a vector
+    auto mapit = freq.begin();
+    for (auto it = lst.begin(); it != lst.end();it++,mapit++){
+        *it = std::make_shared<Node>(Node(mapit->second,mapit->first,NULL,NULL));
+    }
+
+    while(lst.size() > 1){ //Will combine the two smallest Nodes until there is only one node
+        std::sort(lst.begin(),lst.end(),[](std::shared_ptr<Node> l1, std::shared_ptr<Node> l2)->bool{return l1->value < l2->value;});
+
+        if (lst[0]->value < lst[1]->value){
+            lst[1] = std::make_shared<Node>(Node(lst[0]->value + lst[1]->value,'\0',lst[0],lst[1]));
+        }
+        else{
+            lst[1] = std::make_shared<Node>(Node(lst[0]->value + lst[1]->value,'\0',lst[1],lst[0]));
+        }
+
+        lst.erase(lst.begin());
+    }
+
+	_tree = lst[0];
+}
+
+template <class Ptr>
+string preOrder(Ptr curr){
+	if (curr->isLeaf()){
+		return "1" + string(1,curr->letter);
+	}
+	return preOrder(curr->left) + "0" + preOrder(curr->right);	
+}
+
+//NEED NUMBER OF BITS FOR BODY
+string Compress::generateBody(){
+	ifstream inpFile(_fname);
+	if(inpFile.is_open()){
+		if (_bitMap.size()){
+			string line; // Reads input file
+			string compressed = ""; // Will hold compressed body
+			string uncompressed = ""; // Will hold binary string representation of compression
+			while(getline(inpFile,line)){
+				for (char c : line){
+					uncompressed  += _bitMap[c];		
+				}
+			}
+
+			_counter = uncompressed.size();
+
+			//Start to divide the binary string into char
+			int index = 0;
+			char comp;
+			for (char c : uncompressed){
+				if (!index){
+					comp = 0x0;
+				}	
+
+				comp = comp | atoi(&c);
+
+				if (index == 7){
+					compressed += comp;
+				}
+				else{
+					comp = comp << 1; // Shift over one bit
+				}
+				index = (index + 1) % 8;
+			}
+
+			if(index){ // If body is not a multiple of 8, then the last few bits need to be copied into compressed
+				compressed += comp;
+			}
+
+			return compressed;
+		}
+		else{
+			throw("[Error in generateBody()] _bitMap is empty");  
+		}
+	}
+	else{
+		throw("[Error] Could not open file " + _fname + " for generateBody()");
+	}
+}
+
+void Compress::compressFile(string outFile){
+	string body = generateBody();
+	string header = generateHeader();
+	cout << header << endl << body << endl;
+}
+
+string  Compress::generateHeader(){
+	return to_string(_counter) + " " + preOrder(_tree);;
+}

Huffman.H

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+#ifndef __HUFFMAN_H__
+#define __HUFFMAN_H__
+
+#include <map>
+#include <memory>
+#include <string>
+
+using namespace std;
+struct Node;
+
+class Huffman {
+protected:
+	std::string						_fname;
+	std::shared_ptr<Node>			_tree;
+	std::map<char,std::string>		_bitMap; 
+
+	void generateBitMapHelper(shared_ptr<Node> curr, string bin);
+public:
+
+	Huffman(string fname): _fname(fname) , _bitMap(){} 
+
+	virtual ~Huffman(){}
+
+	virtual void generateTree(){};// Will be different for compress and decompress	
+
+	void generateBitMap();
+
+	const map<char,string> & getBitMap(){ return _bitMap;}
+	string getFileName(){return _fname;}
+};
+
+struct Node{
+    double value;
+    char letter;
+    std::shared_ptr<Node> left;
+    std::shared_ptr<Node> right;
+
+    Node(double _value, char _letter, std::shared_ptr<Node> _left, std::shared_ptr<Node> _right) : value(_value), letter(_letter), left(_left), right(_right) {}
+
+    bool isLeaf(){return (!left && !right);}
+};
+
+#endif

Huffman.cpp

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+#include "Huffman.H"
+
+void Huffman::generateBitMapHelper(std::shared_ptr<Node> curr, std::string bin){
+    if(curr->isLeaf()){
+		_bitMap[curr->letter] = bin;
+    }
+    else{
+        generateBitMapHelper(curr->left,bin+"0");
+        generateBitMapHelper(curr->right,bin+"1");
+    }		
+}
+
+void Huffman::generateBitMap(){ //Wrapper class to recursively call enumerateTreeHelper with DFS
+	generateBitMapHelper(_tree,"");
+}

Makefile

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+EXFILES= compress
+FILES= main.o Huffman.o	Compress.o
+FLAGS= -std=c++14 -g
+
+compress: $(FILES)
+	g++ $(FLAGS) $^ -o $@ 
+
+clean:
+	-rm -f *.o $(EXFILES)
+
+%.o: %.cpp
+	g++ $(FLAGS) -c $< -o $@

main.cpp

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+#include "Huffman.H"
+#include "Compress.H"
+
+#include <iostream>
+
+
+int main(int argc, char *argv[]){
+	using namespace std;
+	try{
+		shared_ptr<Compress> conv = make_shared<Compress>(Compress(argv[1]));
+		conv->generateTree();
+		conv->generateBitMap();
+		conv->compressFile("random");
+	}
+	catch(string &e){cout << e;}
+	return 0;
+}

output.txt

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+836 1 01a01u01y01e01m01.01M01T01j01i01s01b01p01g01r01t01w01f01d01v01c01o01h01l01n
+���g]��H2h�}e���A.��F����>�=?qݚ&��Vc�3�6N�u�T,w9�d�O�&�R{�,g�Q�O��o�-]�=���<�Q��pJ4~�nw2pC.�?���c�

test.txt

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+abc

test2.txt

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+hello there my name is tony pham how are you friend. new line. This is just a test to see if the number of bits will actually be less than the compressed version.
+Might as well give it a try and find out