How can i implement a sort algorithm with an array of objects?

Question

I need to create a sort algorithm that takes an array called myArray where there is information from a txt file called start.txt. The problem is that I have inside the txt file many vectors like this: 2 2 30 30, where the first number is the robot number, the second the team, and the last two are the x and y position. I only need to order them in ascending order taking the robot number, but the output has to be the whole vector. Any ideas on how to do it?

#include "robot.h"
#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>
#include <sstream>
#include <cstring>
#include <vector>
    
//class Robot {
//  std::string robotNum;
//  std::string robotTeam;
//  std::string robotPosX;
//  std::string robotPosY;
//  public:
//      Robot(std::string robotNum, std::string robotTeam, std::string robotPosX, std::string robotPosY) {
//          this->robotNum = robotNum;
//          this->robotTeam = robotTeam;
//          this->robotPosX = robotPosX;
//          this->robotPosY = robotPosY;
//      }       
    
//      std::string getRobotNum() {
//          return this->robotNum;
//      }
//      void setRobotNum(std::string robotNum) {
//          this->robotNum;
//      }
    
//};
//void bubbleSort(std::vector<Robot> myArray, int n) {
//int i, j;
//for (i= 0; i<n-1; i++)
    
//}
    
using namespace std;
string line;
std::vector<robot> myArray;
//string* sortArray(string* myArray) {
//bool sortByNum(const robot& lhs, const robot& rhs) { return lhs.robotNum < rhs.robotNum; }
    
    
//return myArray;
//}
void show() {
ifstream myfile;
myfile.open("start.txt");
//string line;
//std::vector<robot> myArray;
    
while (getline(myfile, line))
{
std::istringstream iss(line);
string line;
    
std::string segment;
std::vector<std::string> seglist;
    
while (std::getline(iss, segment, ' '))
{
seglist.push_back(segment);
}
    
//std::vector<robot> myArray;
            
robot robot(seglist[0], seglist[1], seglist[2], seglist[3]);
myArray.push_back(robot);
cout << seglist[0] << " " << seglist[1] << " " << seglist[2] << " " << seglist[3] << "\n";
            
            
//myArray[0].getRobotNum();
            
//for (robot &r : myArray)
//  std::cout << r.getRobotNum() << " _ " << std::endl;
    
//for (unsigned int i = 0; i <= unsigned(myArray.size()); i++) {
            
//}
    
cout << "\n";
}
    
//cout << myArray[];
myfile.close();
    
}
    
int main()
{
    
show();
    
        
return 0;
}

Use std::sort in algorithm header

Tony Tannous
– Tony Tannous

2020-12-14 10:04:41 +00:00
Commented Dec 14, 2020 at 10:04 — Tony Tannous
– Tony Tannous, Commented Dec 14, 2020 at 10:04

john · Accepted Answer · 2020-12-14 10:10:39Z

2

Use std::sort with a custom comparator that only looks at the robot number

#include <algorithm>

std::vector<robot> myArray;
...
sort(myArray.begin(), myArray.end(), 
    [](const robot& x, const robot& y) { return x.getRobotNum() < y.getRobotNum(); }
);

The piece starting with [] is a lambda function that compares two robots using the robot number. This function is passed to std::sort which uses it to sort your vector.

answered Dec 14, 2020 at 10:10

john

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