3

I am trying to create a queue of 2d points, like this:

queue<int[2]> q;

this compiles, however, after doing:

q.push({0,0});

I get an compile error, saying that my call to push is ambiguous. Not sure how to fix this. Please help.

I'm not sure if this is a good way to represent 2d points on a plane, but it seems to me to be the most lightweight.

DawidKubis
  • 31
  • 2
  • 1
    Use `std::array` instead – Alan Birtles Oct 16 '22 at 08:51
  • 1
    Just make a struct (not int[2], and not std::pair) with an x and y value. It is always a good idea to make datatypes that represent a concept. e.g. `struct point_2d { int x; int y; };` (that way you cannot accidentaly pass a int[2] to function intended to work on points) then make a std::queue, or std::vector out of those. – Pepijn Kramer Oct 16 '22 at 08:51
  • @PepijnKramer yeah, a struct fixes it. it does seem like a good idea here. thanks – DawidKubis Oct 16 '22 at 08:59
  • If an answer solves your problem you could click '✔' to mark it as an accepted answer. With enough rep you can _also_ upvote _any_ (and all) helpful answers (see here: https://stackoverflow.com/help/someone-answers). – wohlstad Oct 16 '22 at 13:38

4 Answers4

2

You can use Pair to represent your points.

queue<pair<int,int>>q;
q.push({0,0});
Avish
  • 49
  • 6
0

You can create a structure for the 2D points:

struct Point2D {
    int x;
    int y;
};

And you can create a std::vector instead of std::queue.

std::vector<Point2D> q {{ {1, 2}, {9, 3}, ... }};

And you can normally:

q.push_back({0, 0});

EDIT: You can also create a vector of int[2] instead of Point2D and do the same thing.

Usitha Indeewara
  • 870
  • 3
  • 10
  • 21
0

You can always create a struct to hold your point coordinates. It's actually a good idea to have a representation for such entity regardless of your current problem.

The answer below is a more general one regarding arrays in c++, and does not require a custom struct:

In c++ it's usually recomended to use std::array instead of such small fixed size c style arrays (and std::vector for dynamic size ones).

Code example:

#include <queue>
#include <array>

int main() {
    std::queue<std::array<int,2>> q;
    q.push({ 0,0 });
    return 0;
}

A side note: better to avoid using namespace std - see here Why is "using namespace std;" considered bad practice?.

wohlstad
  • 12,661
  • 10
  • 26
  • 39
0

Array are just pointers. Raw C arrays cannot be stored in container.

Solution 1: Use type of stored element as int*

std::queue<int*> q1;
int s1[2]{0,0};
q1.push(s1);

Solution 2: Use other container like std::array or std::vector

std::queue<std::array<int,2>> q;
q.push({0,0});
Prashant Jagatap
  • 21
  • 2
  • storing the array pointers in the queue is unwise unless the arrays are guaranteed to have longer lifetimes that the queue – Alan Birtles Oct 16 '22 at 16:27
  • Agree! Solutions are just samples of possible ways to solve it. Depending on the use case, use heap or stack, but this is outside the scope of this question. – Prashant Jagatap Oct 16 '22 at 17:41