Line 69 - Position P2(P);

[snowfrogdev]

Hi,

I'm working on a JavaScript port of your Connect4 solver and I'm a bit confused by one line of code. Line 69 in the solver.cpp, inside the negamax algorithm code: ... Position P2(P); ...

seems to be creating an instance of the Position class. What I don't get is that it looks like you are passing the parameter P to the constructor and P is itself an instance of the Position class. What's more, the default constructor function for the Position class does not seem to accept parameters. I'm not proficient in C++ and this maybe why I don't get what is going on here. Could you help. Thanks.

[PascalPons]

it is the default copy contructor.

it is equivalent to: Position P2 = P;

Pascal.

2017-06-20 11:53 GMT-07:00 Philippe Vaillancourt notifications@github.com:

Hi,

I'm working on a JavaScript port of your Connect4 solver and I'm a bit confused by one line of code. Line 69 in the solver.cpp, inside the negamax algorithm code: ... Position P2(P); ...

seems to be creating an instance of the Position class. What I don't get is that it looks like you are passing the parameter P to the constructor and P is itself an instance of the Position class. What's more, the default constructor function for the Position class does not seem to accept parameters. I'm not proficient in C++ and this maybe why I don't get what is going on here. Could you help. Thanks.

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[snowfrogdev]

Wow, good thing you told me about it, I had no idea what it was. So, if I understand correctly, you are basically making a copy of P. Which means that P2 will have the same values as P in its board array? Now I just have to figure the best way to do that in JavaScript. Actually, looking at the code, is a hard copy (clone) really necessary or could P be simply passed by reference? Would it screw up the algorithm?

Man, looking through your code makes me realize that C++ is a very succinct language compared to JavaScript. I especially like the way you populate the entire matrix board with 0s... with one simple line of code. I had to write a whole nested for loop function to do the same thing in JavaScript.

C++

board{0}

vs. JavaScript

this.board = ((numrows, numcols, initial) => {
            const arr = [];
            for (let i = 0; i < numrows; ++i) {
                const columns: number[] = [];
                for (let j = 0; j < numcols; ++j) {
                    columns[j] = initial;
                }
                arr[i] = columns;
            }
            return arr;
        })(Position.WIDTH, Position.HEIGHT, 0);

[MeMeMax]

Neoflash1979 is your code available anywhere?

[snowfrogdev]

@MeMeMax Sorry, I did not complete this project.