Best container for coordinates - c++

Question

I'm currently trying to pick up coordinates from a txt file in use of xlib and I've been wondering what's the best container to use for such an endeavor? I was thinking multidimensional arrays since my program is going to work with triangles and a shortest path algorithm I also wanted to ask how best to fill said container using the scan function too, the plan is to use use nested loops in order to fill it up.
EDIT: The txt file that I'm planning on using is a list of triangle coordinates to draw using the xlib function, Then by placing points on the interface, to find the shortest path from a user-defined spot to another, with the triangles serving as obstacles.
int main(int argc,char *argv[])
{
int A,B;
int Trig[A][B];
FILE * pFile;
// First need to scan the file. Need to check if there's a file to look into first.
std::string pFilename = argv[1];
if (pFilename == ""){
cout << "Needs a Filename";
}
pFile = fopen(atoi(pFilename),"r");
// scanf(pFile,"%1s (%d,%d) (%d,%d) (%d,%d)",);
return 0;
}

Answer 1

If those are 2D coordinates, std::pair would be a great choice.
#include <utility>
int main()
{
std::pair<int, int> intCoordinates(5, 3);
std::cout << "x: " << intCoordinates.first;
std::cout << "y: " << intCoordinates.second << "\n";
// -- hocus pocus, array of pairs, use it as normal C array
std::pair<int, int> arr[5];
}
Of course you can change the type of variables.
It can be <double, double> or even <double, int> if you want, that's completely up to you.
More informations: http://www.cplusplus.com/reference/utility/pair/pair/
In this or any other cases, Point struct would do the job:
struct Point {
int x, y;
Point(int a, int b) { this->x = a; this->y = b; }
};
int main()
{
Point p(2,3);
// ...
}
We probably cannot give your more advices unless you bring us more informations about your code.

Answer 2

I faced the same issue recently and found that post. I started using pair as suggested here but at the end it wasn't that easy to use and to maintain so I created my own Struct with some utilities operators.
.hpp
struct Coordinates
{
std::size_t x;
std::size_t y;
Coordinates(std::size_t x, std::size_t y);
void add(std::size_t x, std::size_t y);
Coordinates operator+=(const Coordinates &coordinate);
Coordinates operator+(Coordinates coordinate);
};
.cpp
Coordinates::Coordinates(std::size_t x, std::size_t y) : x(x), y(y)
{
}
void Coordinates::add(std::size_t xAdd, std::size_t yAdd)
{
x += xAdd;
y += yAdd;
}
Coordinates Coordinates::operator+=(const Coordinates &coordinate)
{
add(coordinate.x, coordinate.y);
return *this;
}
Coordinates Coordinates::operator+(Coordinates coordinate)
{
return coordinate += *this;
}
Here is what you can do:
Coordinates myPoint(4, 7);
myPoint += Coordinates(2, 3); // myPoint now contains x = 6 and y = 10
You can also access fields x and y by doing yourPoint.x or yourPoint.y.