LNK2019 Unresolved External Symbol Help Please [duplicate] - c++

Question

This question already has answers here:
What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 8 years ago.
I'm trying to test a program and every time I go to compile it, I get the error LNK2019: unresolved external symbol "public: __thiscall Prog3Graph::Prog3Graph(void)" (??0Prog3Graph##QAE#XZ) referenced in function _main. I was wondering what is causing this and how I can fix it. I've tried messing around with the code, but can't figure what is causing it.
Prog3Graph.cpp:
#include <iostream>
#include <fstream>
#include <string.h>
#include <stdlib.h>
#include "Prog3Graph.h"
#include "GraphNode.h"
using namespace std;
int main()
{
Prog3Graph *test;
test = new Prog3Graph();
test->buildGraph("Graph.txt");
test->printGraph();
return 0;
}
bool Prog3Graph::buildGraph(char *fileName)
{
int i,j,index,numlinks, link;
char line[24];
ifstream inFile;
inFile.open(fileName, ifstream::in);
if(!inFile.is_open())
{
cout << "Unable to open file " << fileName << ". \nProgram terminating...\n";
return 0;
}
for(i=0;i<10;i++)
{
getNextLine(line,24);
index = atoi(line);
Nodes[i].setNodeID(index);
getNextLine(line,24);
Nodes[i].setNodeData(line);
getNextLine(line,24);
numlinks = atoi(line);
for(j=0;j<numlinks;j++)
{
getNextLine(line,24);
link = atoi(line);
AdjMatrix[i][link]=1;
}
inFile.close();
}
return true;
}
void Prog3Graph::printGraph()
{
int i,j;
cout << "------------------------------------------------------------\n\n";
cout << " Adjacency Matrix:\n\n";
cout << " 0 1 2 3 4 5 6 7 8 9\n";
cout << " +---------------+\n";
for(i=0; i<10; i++)
{
cout << i << "|";
for(j=0; j<10; j++)
{
cout << AdjMatrix[i][j] << "|";
}
cout << "\n +---------------+\n";
}
}
bool Prog3Graph::getNextLine(char *line, int lineLen)
{
int done = false;
ifstream inFile;
while(!done)
{
inFile.getline(line, lineLen);
if(inFile.good())
{
if(strlen(line) == 0)
continue;
else if(line[0] == '#')
continue;
else done = true;
}
else
{
strcpy(line, "");
return false;
}
}
return true;
}
Prog3Graph.h:
#pragma once
#include <iostream>
#include <fstream>
#include <string.h>
#include <stdlib.h>
#include "GraphNode.h"
using namespace std;
class Prog3Graph
{
private:
ifstream inFile; // File stream to read from
int AdjMatrix[10][10];
GraphNode Nodes[10];
public:
Prog3Graph(); // Class constructor
~Prog3Graph(); // Class destructor
bool buildGraph(char *filename); // Read graph file, build graph
void printGraph(); // Print all data in graph
void depthFirstTraversal(); // Perform a depth first traversal
private:
bool getNextLine(char *line, int lineLen); // Read next line from graph file
};
GraphNode.cpp:
#include <iostream>
#include <fstream>
#include <string.h>
#include <stdlib.h>
#include "GraphNode.h"
using namespace std;
void GraphNode::setNodeID(int ID)
{
m_iNodeID = ID;
}
int GraphNode::getNodeID()
{
return m_iNodeID;
}
void GraphNode::setNodeData(char *data)
{
int i;
for(i=0;i<24;i++)
{
m_sNodeData[i] = data[i];
}
}
char *GraphNode::getNodeData()
{
return &m_sNodeData[24];
}
void GraphNode::setVisited(bool visited)
{
m_bVisited = visited;
}
bool GraphNode::hasBeenVisited()
{
return m_bVisited;
}
GraphNode.h:
#pragma once
#include <iostream>
#include <fstream>
#include <string.h>
#include <stdlib.h>
using namespace std;
class GraphNode
{
private:
int m_iNodeID;
char m_sNodeData[24];
bool m_bVisited;
public:
GraphNode();
~GraphNode();
void setNodeID(int ID);
int getNodeID();
void setNodeData(char *data);
char *getNodeData();
void setVisited(bool visited);
bool hasBeenVisited();
};

Answer 1

Read the message carefully:
unresolved external symbol "public: __thiscall Prog3Graph::Prog3Graph(void)" (??0Prog3Graph##QAE#XZ) referenced in function _main.
You've declared a constructor (and a destructor) for your class, but you've never actually defined them.