Receiving error: "error: static assertion failed: result type must be constructible from value type of input range" when constructing class vectors

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• C++ increment with macro

  I have the following code and I want to use increment with macro:

  #include <iostream>
  
  #define ABS(x) ((x) < 0 ? -(x) : (x))
  
  int main(int argc, char** argv)
  {
      int x = 5;
      const int result = ABS(x++);
  
      std::cout << "R: " << result << std::endl;
      std::cout << "X: " << x << std::endl;
  
      return EXIT_SUCCESS;
  }
  

  But output will be incorrect:

  R: 6
  X: 7
  

  Is it possible to somehow use macros with an increment, or should this be abandoned altogether?
• Can anyone pls tell me whats wrong with my code ? im stuck for the last 3 hours ,this question is bipartite graph in c++

  idk why im getting error ,can someone help ? im trying to prove if a graph is bipartite or not in c++

  
  bool isBipartite(vector<int> graph[],int V)
  {
      vector<int> vis(V,0);
      vector<int> color(V,-1);
      
      color[0]=1;
      queue <int> q;
      q.push(0);
      while (!q.empty())
      {
          int temp = q.front();
          q.pop();
          for (int i=0;i<V;i++)
          {
              if (!vis[i] && color[i] == -1)   "if there is an edge, and colour is not assigned"
              {
                  color[i] = 1 - color[temp];
                  q.push(i);
                  vis[i]=1;
              }
              else if (!vis[i] && color[i] == color[temp] "if there is an edge and both vertices have same colours"
              {
                  vis[i]=1;
                  return 0;                                // graph is not bipartite
              }
                  
              
          }
      }
      return 1;
  }
  
  

  it gives output "no" for whatever i enter
• How to assign two or more values to a QMap Variable in Qt

  I am getting confused of how to store the values assigned from 3 different functions and storing them in a single map variable

  QMap<QString,QString> TrainMap = nullptr;   
  if(......)    
  (    
         TrainMap    =    PrevDayTrainMap();
         TrainMap    =    NextDayTrainMap();
         TrainMap    =    CurrentDayTrainMap();
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  The PrevDayTrainMap,NextDayTrainMap & CurrentDayTrainMap returns a set of values with Date and the TrainIdName.I need to store all the values from prevday,currentday and nextday in the TrainMap but it stores only the currentday values to the TrainMap as it is assigned at the last.I am not sure what to do so that it doesn't overwrite.If I should merge what is the way to do it?
• Read each name in Array list to create seperate object for

  I have a file that has student names, age, and an id number. I have a student class that holds the everything above for each student object. I stored all the names, id numbers. and age separately in an array list. Now im trying to assign the info to create a student object.

  public class Student {
      private String lName;
      private int idNumber;
      private int age;
  
      public Student() {
          lName = "";
          idNumber = 0;
          age = 0;
      }
      public Student(String l, int i, int a) {
          lName = l;
          idNumber = i;
          age = a;
      }
  
      public void setName(String last) {
          lName = last;
      }
  
      public String getName() {
          return lName;
      }
  
      public void setIdNum(int num) {
          idNumber = num;
      }
  
      public int getIdNum() {
          return idNumber;
      }
  
      public void setAge(int a) {
          age = a;
      }
  
      public int getAge() {
          return age;
      }
  }
  

  My Text File looks something like this: This info is stored in parallel array lists. I don't quite get how to implement this into an object to pass it into my second contractor method.

    Josh          2134         19
    Smith         5256         21
    Rogers        9248         19
    Andrew        7742         20
  

  Here's what I've tried;

  public static void main(String[] args) {
      String file = "studentData.txt";
      Scanner reader = new Scanner(file);
  
      ArrayList<String> lastNames = lNames(file);
      ArrayList<Integer> idNumbers = idNum(file);
      ArrayList<Integer> ageList = ages(file);
  
      Scanner input = new Scanner(System.in);
  
      Student s1 = new Student();
  
      // confused about how to implement this constructor with the textile info
      for (int i = 0; i<idNumbers.size(); i++) {
          Student user = new Student(lastNames.get(i), idNumbers.get(i), ageList.get(i));
      }
  
      //user enters idNumber to display age
      System.out.println("Enter ID Number"); //exception handling to be added
      int idNum = input.nextInt();
  
      for (int i = 0; i<idNumbers.size(); i++) {
          if (idNum == idNumbers.get(i)) {
              s1.setAge(ageList.get(i));
              System.out.println(s1.getAge());
  
          }
      }
  }
  
• Custom utility types (generic types) for classes `IsClass` of TypeScript

  I am trying to create a generic type to make sure the first parameter to be a class. However, the factory function parameter cannot be replaced by a generic type.

  The following upper parts were my attempts. The last part were a working example that directly write the extends ... which worked.

  Why does it works inside a function, but not works as a generic type IsClass?

  class A {
    constructor() {
  
    }
  }
  class B {}
  class C extends B {}
  
  // ERRORS:
  
  type IsClass<T extends new (...args: any) => InstanceType<T>> = T
  type IsClass2<T> = T extends new (...args: any) => InstanceType<T>? T: never
  
  type X = IsClass<A>
  type Y = IsClass2<A>
  
  function someFactoryError<T>(clx: IsClass<T>) {
    return new clx()
  }
  
  someFactoryError(A)
  
  function someFactoryError2<T>(clx: IsClass2<T>) {
    return new clx()
  }
  
  someFactoryError2(A)
  
  // WORKS:
  
  function someFactoryWorks<T extends new (...args: any) => InstanceType<T>>(clx: T) {
    return new clx()
  }
  
  const a0 = someFactoryWorks(A)
  const b0 = someFactoryWorks(B)
  

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  I am not an expert coder and I have just started learning about Generic data types. What I am trying to code is a List inside of a list inside of a list .

  For example- at the first level - I want numbers each inside of a list

  Layer 1 list1=[1,2,3,4,5,6,7,8,9,10......1000] ,

  At the 2nd layer I'd like list from 1st layer added as an element to a parent list 2 when layer 1 meets certain condition- ex layer 1 reaches max=10

  List2=[List1[0:10],List1[10:20],List1[20:30], .....] ,

  At layer 3, i'd like to repeat the process, all elements of layer 2 get added as an element to a new parent list 3 when layer 2 meets a max condition. list3[0]=[list2[0:10],list2[10:20],list2[20:30]..... and so on.

  Only the first layer would have integer values, the successive layer would be a wrapping of it's the previous layer. How can I code this in C#?

  Thanks!
• Im having trouble with this assignment that has me write vectors and arrays to a file

  So in this assignment I have to have one function that has the user enter the vector which is the driver name and then they enter the drivers 4 points. That function is fine. I also Have to do a second function that writes the name and the average that I get from the 4 points to the txt file. and then display the name and averages in main. Right now I am stuck on the second function because I'm having trouble getting it to where it would write the vector and then the average after it. right now it is writing both vector elements and then the first average, and then both vector elements and the second average. can someone help me

  #include <iostream>
  #include <string>
  #include <cmath>
  #include <iomanip>
  #include <vector>
  #include <fstream>
  using namespace std;
  
  //function prototypes
  void Enter_Driver_Data(vector<string> &driverName, int points[8][4], string fileName, fstream& file, int& counter);
  void Calculate_Average(vector<string> &driverName, int points[8][4], string fileName, fstream& file, int& counter);
  
  int main()
  {
      int counter = 0;//this counter is for the average function
      int points[8][4];
      vector<string>driverName;
      fstream file;
      string fileName;
      int average;
  
  
      //user will enter a text file name
  
      cout << "Please enter the file name: ";
      getline(cin, fileName);
  
      Enter_Driver_Data(driverName, points, fileName, file, counter);
      Calculate_Average(driverName, points, fileName, file, counter);
      cout << setprecision(1) << fixed << endl;
  
      fstream txtInput(fileName, ios::in);
      //outputting the txt file data
      for (string i : driverName)
      {
          cout << i << "'s average points is: ";
          txtInput >> average;
          cout << endl;
  
      }
      
  
      
      cout << endl << endl;
      system("pause");
      return 0;
  }
  void Enter_Driver_Data(vector<string> &driverName, int points[8][4], string fileName, fstream& file, int& counter)//this function is for entering data
  {
      file.open(fileName, ios::out);
  
      string driverNameInput;
      //filestream declarations
      fstream txtOutput(fileName, ios::out);
      
  
      //again declaration
      bool again = true;
      //for loop for data
      for (int name = 0; name < 8 && again; name++)//name is for the row of the array
      {
          cout << "\nPlease enter the driver's name: ";
          getline(cin, driverNameInput);
  
          driverName.push_back(driverNameInput);
          txtOutput << driverName[name] << ": ";
  
          for (int score = 0; score < 4; score++)//score is for the column of the array
          {
  
              cout << "\nPlease enter " << driverName[name] << "'s score number " << score + 1 << ": ";
              cin >> points[name][score];
              while (points[name][score] != 60 && points[name][score] != 70 && points[name][score] != 80 && points[name][score] != 90 && points[name][score] != 100)
              {
                  cout << "Your input was invalid: please enter the scores which are 60, 70, 80, 90,or 100: ";
                  cin >> points[name][score];
              }
              cout << points[name][score] << endl;
              txtOutput << points[name][score] << " ";
              
              cin.ignore();
              cin.clear();
          }
          txtOutput << endl;
          cout << "Would you like to enter another driver?(1 for yes and 0 for no): ";
          cin >> again;
          cin.ignore();
          cin.clear();
          counter++;
          
      }
      file.close();
  }
  void Calculate_Average(vector<string> &driverName, int points[8][4], string fileName, fstream& file, int& counter)
  {
      file.open(fileName, ios::app);
      fstream txtOutput(fileName, ios::app);
      double totalBeforeAverage, average;
      vector <double> avg;
      for (int name = 0; name < counter; name++)
      {
          totalBeforeAverage = 0, average = 0;
  
          for (int score = 0; score < 4; score++)
          {
              totalBeforeAverage += points[name][score];
          }
          average = totalBeforeAverage / 4;
          avg.push_back(average);
      }
      for (string drivName : driverName)
      {
          txtOutput << drivName << ": ";
  
      }
      for (double averageToFile : avg)
      {
          txtOutput << averageToFile << endl;
      }
      file.close();
      
  }
  
  
• Attempting to solve this problem more efficiently

  I read a natural number with at most 9 digits. I have to form a vector with the even digits of that number, in ascending order, with each digit appearing once (example : 98762222 is going to output: 2 6 8). I want to know what optimisations can I add to this code to make it more efficient.

  #include <iostream>
  
  using namespace std;
  
  int main()
  {   int x,i,k=0,copy,v[10]={0},j;
      cout<<"x=";
      cin>>x;
      copy=x;
      if (x==0)
          cout<<0;
      while (x>0)
      {
          v[x%10]++;
          x/=10;
      }
      for (i=0; i<10; i=i+2)
      {
          if(v[i]>0)
          {
            k++;
          }
      }
      int w[k]={0};
      if (k>0)
       {  j=0;
          for (i=0; i<10; i=i+2)
            if(v[i]>0)
             {   w[j]=i;
                 j++;}
       }
  
      for (j=0; j<k; j++)
          cout<<w[j]<<" ";
      if (k==0 && copy!=0)
       cout<<"No even digits";
      return 0;
  }
  
• Scala argument upper type bounds and overriding

  I am trying to understand and incorporate upper bound types with overriding in my system, but have not been able to achieve it without some ugly code. I have the following 2 traits:

  trait MyId {
    def getType: Int // For simplicity. This is Enum/Object in code.
    def id: Any
  }
  
  trait MyTrait {
    protected def supportedType: Int
   
    def doSomething(id: MyId): Unit = {
      if (id.getType == myType) 
        doSomethingInternal(id)
    }
    
    protected def doSomethingInternal(id: _ <: MyId): Unit
  }
  

  and I want to create subtypes as:

  class X(x: Long) extends MyId {
    override def getType: Int = 1
    override def id: Long = x
  }
  
  class Y(y: String) extends MyId {
    override def getType: Int = 2
    override def id: String = y
  }
  
  class A extends MyTrait {
    override protected def supportedType: Int = 1
  
    override protected def doSomethingInternal(id: X): Unit {...}
  }
  
  class B extends MyTrait {
    override protected def supportedType: Int = 2
  
    override protected def doSomethingInternal(id: Y): Unit {...}
  }
  

  However, this does not work. The workaround I have been using is to use asInstanceOf[]:

  class A extends MyTrait {
    override protected def supportedType: Int = 1
  
    override protected def doSomethingInternal(id: MyId): Unit {
      val id2 = id.asInstanceOf[X]
    }
  }
  
  class B extends MyTrait {
    override protected def supportedType: Int = 2
  
    override protected def doSomethingInternal(id: MyId): Unit {
      val id2 = id.asInstanceOf[Y]
    }
  }
  

  Is there a way I can get rid of the asInstanceOf[]?

  EDIT

  Further more, I have the following processor which requires calling the correct MyTrait subclass based on the given MyId.getType:

  def process(ids: Seq[MyId], processors: Map[Int, MyTrait]): Unit = {
    ids.foreach{ id =>
      processors.get(id.getType).doSomething(id)
    }
  }
  

  Edit 2:

  • getType is Int for simplicity here. This is actually an enum/object in my code.
  • Renamed getSomething to doSomething for more clarity.
• Need to Implement scenario using OOP method in C#

  Following is the question and in the end there is an expected output. I need some guidance on interface part, need guidance how it need to be done.

  UML Diagram

  Task