Reading from file and storing attributes gives wrong output

Question

I'm trying to read a text file that consists of the following three attributes;

RouterID, X-coordinate, Y-coordinate .

A brief snippet of the txt file is shown below;

100 0       0
1   20.56   310.47
2   46.34   219.22
3   240.40  59.52
4   372.76  88.95

Now, what I'm trying to achieve is to make a node for every RouterID and store its corresponding x and y co-ordinates. For this purpose, I have created the following class;

class Node {

public:
    float routerID;
    float x;
    float y;

    void set_rid (float routerID) {
        routerID = routerID;
    }

    void set_x_y (float x, float y) {
        x = x;
        y = y;
    }

};

And I have the following which performs the job of creating a new node for every routerID;

const std::string fileName = "sampleInput.txt";
std::list<Node> nodeList;

int main (void) {

    std::ifstream infile(fileName);

    float a(0);
    float b(0), c(0);

    //This reads the file and makes new nodes associated with every input
    while (infile >> a >> b >> c) {
        Node newNode;
        newNode.set_rid (a);
        newNode.set_x_y (b, c);
        std::cout << "newNode " << "rid = " << newNode.routerID << " x = " << newNode.x << " y = " << newNode.y << std::endl;
        nodeList.push_back(newNode);
    }

I'm performing the following line inside my while loop just to check whether or not the values being assigned are correct or not.

std::cout << "newNode " << "rid = " << newNode.routerID << " x = " << newNode.x << " y = " << newNode.y << std::endl;

When I compile and run the code, I get the following as my output for all of them;

newNode rid = -1.07374e+008 x = -1.07374e+008 y = -1.07374e+008

I've just started learning C++ last week and this is my first "big" program that I am trying to code. Could anyone please point me in the right direction?

Answer 1

void set_rid (float routerID) {
    routerID = routerID;
}

This doesn't do what you seem to think it does. It assigns the parameter to itself; the value of this->routerID remains unchanged. Same with set_x_y . Just give the method parameters some names that are different from those of data members.

Answer 2

Another to distinguish class variables from input parameter is by using the keyword this. thus you can make a reference to class variables by calling this.routerID, this.x and this.y