how to store elements in a 2d vector and call them out.

[CLearner88]

Hi guys, i`m currently trying to implement a 2d vector to store x and y of type int.

i have successfully passed it to the function, however i am unable to store the values in it. It always returns with a segementation fault and my program terminates from there. May i know how do i store them properly and call them out?

below is my code snippet

int reconstructSecret(int x, int y, vector< vector<int> > &inVec ,int constructSecret)
{
    int getX,getY,formula,accum,count,getSecret,startPosition,nextPosition,numerator,denominator;
    getX=x;
    getY=y;
    int result;
    int getSecret2=constructSecret;

    inVec.push_back(vector<int> (,getY));

    for(int i=0;i<getSecret2;i++)
    {
        for(int j=0;j<getSecret2;j++)
        {
            cout<<inVec[i][j]<<endl;
        }
    }
}

the main method

vector< vector<int> > inVec;

    for(int i=0;i<constructSecret;i++)
    {
        cout<<"please key in the "<<i<< "share of x value:";
        cin>>x;
        cout<<"please key in the "<<i<< "share of y value:";
        cin>>y;
        reconstructSecret(x,y,inVec,constructSecret);

    }

Thanks in advance!

[Daleth]

What is the comma doing on line 9? Also you are attempting to call the constructor? I am not sure if that is okay to do, but I've never tried it before.

[CLearner88]

sorry about that comma, it was an edit mistake.

the updated code is here

int reconstructSecret(int x, int y, vector< vector<int> > &inVec ,int constructSecret)
{
    int getX,getY,formula,accum,count,getSecret,startPosition,nextPosition,numerator,denominator;
    getX=x;
    getY=y;
    int result;
    int getSecret2=constructSecret;

    inVec.push_back(vector<int> (getX,getY));

    for(int i=0;i<getSecret2;i++)
    {
        for(int j=0;j<getSecret2;j++)
        {
            cout<<inVec[i][j]<<endl;
        }
    }
}

i`m trying to store x and y coordinates into this 2d vector so that i can call them out to use in a formula

[CLearner88]

ok maybe i misunderstood the concept about 2D vectors.

i`m trying to store two values x and y which the user keys in
So i thought of using a 2D array , in order to store x=1 and y = 23 into a 2D vector.

so when i call out vector[0][0], it will give me x = 1 and y = 23.

does a 2D vector works this way? correct me if i`m wrong

[Daleth]

Well, if you are creating a temporary vector container to push back, I suggest using the initializer_list braces.
e.g.

vector<int> Myvector({getX,getY});
//Equivalent to:
vector<int> Myvector = {getX,getY};

You can check the reference section to make sure.

[CLearner88]

nope, i still have the same segmentation fault.

this is driving me nuts lol

[Daleth]

Did you try creating a temporary container outside that's initialized with your variables and then push that to your inVec? I'm pretty sure trying to call any constructor straight up is not good, though I don't remember why.

[CLearner88]

i shall try it in a test class.

anyway, is there anyway to store the values that i have gotten from user input

lets say x is 10 and y is 23 , i want to store them in an array that is myArray[0][0] so when i call out position 0 and 0 of the array they will return the values 10 and 23

[Daleth]

No unfortunately. Just like with regular arrays, the container will do this:
Array of arrays --[0]--> Array of ints at position 0 --[0]--> int at position 0,0

However, you can have:
Array of arrays --[0]--> Array of ints ----> Access getX and getY stored in array.

But if for some reason you need that extra dimension, then you're going to have to use 3D vector container...

[CLearner88]

hmm ok thank you. Think i will look for other alternatives for that
Thanks for your help!