Sort a vector of classes

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So I have a class node(name, vector, distance, prev) and i want to sort it by distance. And i have used some methods like sort or with a operator but nothing seems to work. Is there any other way to to sort a vector of classes?

What I have tried:

I also used

sort( test.begin(), test.end(), [](const node &a, const node &b){ return (a.distanceToStart < b.distanceToStart);});

but i get a lambda error codes.

error: no match for call to '(main()::<lambda(const node&,="" const="" node&)="">) (node*&, node*&)'
158 | { return bool(_M_comp(*__it1, *__it2)); }

node a = node("a",{}, 15, &a); node b = node("b",{}, 14, &a); node c = node("c",{}, 25, &a); node d = node("d", {}, 1, &a); node e = node("e", {}, INT_MAX, &a);

#include <iostream>
#include <vector>
using namespace std;

class edge;


class node{

public: 
    string name;
    node* prev;
    vector<edge*> edges;
    int distanceToStart;

    node(string name, vector<edge*> edges, int distanceToStart, node* prev){
        this ->distanceToStart = distanceToStart;
        this ->edges = edges;
        this ->name = name;
        this ->prev = prev;
    }

    int getDistanceToStart(){
        return distanceToStart;
    }

    void setDistanceToStart(int d){
        distanceToStart = d;
    }

};

Posted 28-Jun-23 3:42am

Quinten Bakker (QB)

Updated 28-Jun-23 5:35am

v2

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Quinten Bakker (QB) 28-Jun-23 9:48am

Forget the erro code
error: no match for call to '(main()::<lambda(const node&,="" const="" node&)="">) (node*&, node*&)'
158 | { return bool(_M_comp(*__it1, *__it2)); }

Patrice T 28-Jun-23 10:13am

Use Improve question to update it.
Your comment will get more attention if inside the question.

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k5054 · Answer 1 · 2023-06-28T04:30:00

I added a main function the above code vis:

C++

// .. QB's code up to here 
#include <algorithm>

int main()
{
    vector<node> test;
    sort( test.begin(), test.end(), [](const node &a, const node &b){ return (a.distanceToStart < b.distanceToStart);});
}

This compiles without error using GCC, Clang and MSVC. Either you've managed to correct your lambda, or there is something else in your code that's causing problems. Maybe start by removing the using namespace std; directive and explicitly use the std namespace as needed.

If you're using separate compilation of your classes, then you should not be using namespace std; in the class header file. Doing so means that anything that does an #include "myclass.hpp" will also import all of the std namespace, which might cause unexpected results.

Richard MacCutchan · Answer 2 · 2023-06-28T05:35:00

I have simplified your node class and the following code builds and runs using Microsoft C++ compiler:

C++

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>

class node{
public: 
    std::string name;
    int distanceToStart;

    node(std::string name, int distanceToStart)
    {
        this ->distanceToStart = distanceToStart;
        this ->name = name;
    }

    int getDistanceToStart(){
        return distanceToStart;
    }
};

int main()
{
    node a("a", 15);
    node b("b", 14);
    node c("c", 25);
    std::vector<node> test;
    test.push_back(a);
    test.push_back(b);
    test.push_back(c);

    std::sort( test.begin(), test.end(), [](const node &a, const node &b){ return (a.distanceToStart < b.distanceToStart);});
    for (auto n : test)
    {
        std::cout << "Node " << n.name << " " << n.distanceToStart << std::endl;
    }
}

Sort a vector of classes

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