Im on my journey to refresh my c++ skills, for upcoming project in 2-3 weeks.
Im implementing a command line program that given input adjacency list 1>2;2>3;3>1,3,4 were ">" actually means -> path to. Will generate a internal adjacency matrix, then using Dijkstra print the shortest paths.
Im while implementing Dijkstra, Im suddenly getting a in short "unresolved external symbol "public: __thiscall Node::Node(void)"
Here is the whole error msg:
Error error LNK2019: unresolved external symbol "public: __thiscall Node::Node(void)" (??0Node@@QAE@XZ) referenced in function "void __cdecl Dijkstra(class std::vector<class std::vector<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::allocator<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > >,class std::allocator<class std::vector<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::allocator<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > > > > const &)" (?Dijkstra@@YAXABV?$vector@V?$vector@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V?$allocator@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@2@@std@@V?$allocator@V?$vector@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V?$allocator@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@2@@std@@@2@@std@@@Z) C:\Users\ary\Documents\visual_studio_code\examples\CourseraC_plus_plus_for_C_1\week2\shortest_path'\shortest_path'\shortest_path'.obj shortest_path'
Here is main class:
Here is the main entry cpp:
// shortest_path'.cpp : Defines the entry point for the console application.
#include "stdafx.h"
//This software takes in 2-dimensional vertices {x,y} as input and constructs a adjacency matrix internally.
//Then the software will use shortest path algorithm to display all the shorterst paths from a
//start node to other nodes.
#include <iostream>
#include <string>
#include <vector>
#include <map>
#include "Node.h"
using namespace std;
//signature for menu function
void menu();
//sub menu option and capture input for vertices
void inputVerticesSubMenu();
//split the vertices into tokens
vector<string> splitVerticesInputString(const string&, char);
//create 2d arrat to represent adjacency matrix
vector<vector<string>> adjacencyMatrix(const vector<string>&);
//shortest path
void Dijkstra(const vector<vector<string>>& adjacency);
//visited Nodes
vector<Node*> visited;
//not visited
vector<Node*> notVisited;
int numberOfUniqueNodes = 0;
int main()
{
int input;
menu();
cin >> input;
while (input != -1)
{
//what option was selected
switch (input)
{
cout << "input: " << input;
case 1:
cout << "case 1" << endl;
inputVerticesSubMenu();
break;
case 2:
cout << "case 2" << endl;
break;
case 3:
cout << "case 3" << endl;
input = -1;
return 0;
default:
cout << "invalid option!" << endl;
menu();
cin >> input;
break;
}//end option switch
menu();
cin >> input;
}
};
void menu()
{
cout << "" << endl;
cout << "1) enter vertices" << endl;
cout << "2) compute shortest path via Dijkstra (use option 1 first)." << endl;
cout << "3) exit" << endl;
}
void inputVerticesSubMenu()
{
cout << "Example if you have a graph with vertices 1,2,3." << endl;
cout << "If 1 points to 2, and 2 points to 3, and 3 points back to 1 & itself." << endl;
cout << "Then enter 1>2;2>3;3>1,3. Then press Enter when done." << endl;
cout << "This will create a internal adjacency matrix which will be printed as a check." << endl;
cout << "Enter vertices:" << endl;
string inputVertices;
cin >> inputVertices;
cout << "Please enter number of unique nodes (For example 1>2;2>3;3>1,3 has 3 nodes):" << inputVertices << endl;
cin >> numberOfUniqueNodes;
vector<string> tokens = splitVerticesInputString(inputVertices, ';');
string token;
map<string, string> uniqueNodes;
vector<vector<string>> adjacency = adjacencyMatrix(tokens);
cout << "adjacency matrix:" << endl;
Dijkstra(adjacency);
cout << "Then select Option 2 to start Dijkstra computation!" << endl;
}//end inputVerticesSubMenu()
vector<string> splitVerticesInputString(const string& inputVertices, char delimiter)
{
vector<string> tokens;
string token;
int start = 0;
int end = 0;
for (int i = 0; i <= inputVertices.length(); i++)
{
//cout << inputVertices[i] << endl;
if (inputVertices[i] == delimiter || i == inputVertices.length())
{
end = i;
int length = (end - start);
token = inputVertices.substr(start, length);
tokens.push_back(token);
start = end + 1;
}//ednd if token is found
}//end for
return tokens;
}
vector<vector<string>> adjacencyMatrix(const vector<string>& tokens)
{
vector<vector<string>> adjacency;
string token;
//create row of vectors based on number of numberOfUniqueNodes
for (int c = 0; c < numberOfUniqueNodes; c++)
{
//the vector should be of size numberOfUniqueNodes & initialized to 0
vector<string> rowVector(numberOfUniqueNodes, "0");
adjacency.push_back(rowVector);
}//end loop
//parse tokens in vectors ,ane create a simulated matrix in vector<vector<string>>
for (int i = 0; i < tokens.size(); i++)
{
//1st split from to get originating node , then ending connection nodes
token = tokens.at(i);
//cout << "token:" << token << endl;
std::size_t found = token.find('>');
if (found != std::string::npos)
{
string fromNode = token.substr(0, found);
string neighborNodes = token.substr(found + 1, token.size() - found);
cout << "vertice=" << fromNode << ">" << neighborNodes << endl;
int row = atoi(fromNode.c_str()) - 1;
vector<string> row_vector = adjacency.at(row);
//parse the neighborNodes string using
vector<string> columns = splitVerticesInputString(neighborNodes, ',');
for (int k = 0; k < columns.size(); k++)
{
int offset = atoi(columns.at(k).c_str());
//TODO : columns
row_vector.at(offset - 1) = "1";
}
//persist back
adjacency.at(row) = row_vector;
}
else
{
cout << "vertice=" << token << endl;
}
}//end
return adjacency;
}//end vector<vector<string>> adjacencyMatrix(const vector<string>& tokens)
void Dijkstra(const vector<vector<string>>& adjacency)
{
Node *currentNode = new Node();
//print the adjacency matrix for the matrix & initialize univisited vector
for (int r = 0; r < adjacency.size(); r++)
{
//instantiate new Node from adjacency matrix
currentNode->setLabel(std::to_string(r + 1));
currentNode->setWeight(1);
vector<string> row_vector = adjacency[r];
for (int c = 0; c < row_vector.size(); c++)
{
//add neighbors
std::cout << row_vector.at(c);
if (row_vector.at(c) == "1")
{
Node *neighbor = new Node();
neighbor->setLabel(std::to_string(c + 1));
neighbor->setWeight(1);
//set prev link to parent/originating Node
neighbor->setPrev(currentNode);
currentNode->addNeighborNode(neighbor);
}
}
//add to notVisited vector
notVisited.push_back(currentNode);
std::cout << endl;
}//end
cout << "Linked list of nodes" << endl;
}//end
Node header:
#ifndef NODE_H
#define NODE_H
#include <string>
#include <vector>
using namespace std;
class Node
{
public:
Node();
Node(string label);
~Node();
void setLabel(string value);
string getLabel();
void setWeight(int value);
int getWeight();
void addNeighborNode(Node* node);
vector<Node*> getNeighbors();
void setPrev(Node* node);
Node* getPrev();
Node& operator=(const Node& other);
private:
string _label;
int _weight =0;
vector<Node> _neighbors;
Node* _prev;
};
#endif
Node implementation cpp:
#include "Node.h"
Node::Node()
{
}
Node::Node(string label)
{
_label = label;
}
Node::~Node()
{
}
/*
void setLabel(string value);
string getLabel();
*/
Node::setLabel(string value)
{
_label = value;
}
string Node::getLabel()
{
return _label;
}
/*
void setWeight(int value);
int getWeight();
*/
Node::setWeight(int value)
{
_weight = value;
}
int Node::getWeight()
{
returtn _weight;
}
/*
void addNeighborNode(Node& node);
vector<Node> getNeighbors(); */
Node::addNeighborNode(Node* node)
{
_neighbors.push_back(node);
}
vector<Node*> ode::getNeighbors()
{
return _neighbors;
}
/*
void setPrev(Node& node);
Node& getPrev();
*/
Node::setPrev(Node* node)
{
_prev = node;
}
Node* Node::getPrev()
{
return *_prev;
}
Node& operator=(const Node& other) // copy assignments
{
if (this != &other) { // self-assignment check expected
_label = other._label;
_weight = other._weight;
_prev = other._prev;
_neighbors = other._neighbors;
}
return *this;
}
This error occurs when I try to instantiate a pointer of type Node in the 1st line after the void Dijkstra(const vector<vector<string>>& adjacency) function signbature Node *currentNode = new Node();. Naturally I would think Node() constructor is not implemented in cpp but it is, then I looked at other functions & they were also ok.
I also know Dijkstra is not completed, Im waiting to resolve this issue 1st.
Any help will be appreciated.
Thanks
