CODEWITHSUNDEEP
c++
user6549804
user6549804

Reputation:

Why am I getting "Candidate constructor not viable"?

#include <stdio.h>
#include <vector>
#include <iostream>
#include <algorithm>

using namespace std;

struct Node1 {
    unsigned int vertex;
    unsigned int representative;
    Node1(unsigned int Vert, unsigned int Rep) : vertex(Vert), representative(Rep) {}
};

class Graph{
    vector<Node1> nodes;
public:

    void findComponents() {
        nodes.emplace_back(1, 1);
        nodes.resize(1);
//        nodes.resize(newSize);
    }
};

int main(){
    Graph g;
    g.findComponents();
}

I'm getting a ton of weird build errors mainly consisting of "Candidate constructor not viable" and " In instantiation of member function 'std::__1::vector >::resize' requested her"

Upvotes: 0

Views: 1706

Answers (1)

P.W
P.W

Reputation: 26800

To use the below overload of vector::resize() which you are using in your code, T must meet the requirements of MoveInsertable and DefaultInsertable. 

void resize( size_type count );

DefaultInsertable means that an instance of the type can be default-constructed in-place.

So what you need is a default constructor for Node1. For that you can do this:

Node1() = default;

Or specify default values for Vert and Rep in the existing constructor like this:

Node1(unsigned int Vert = 0, unsigned int Rep = 0) : vertex(Vert), representative(Rep) {}

Upvotes: 3

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