Swap Struct in C++

[Shervan360]

Hello,
I want to swap elements of an array but I have an error. Why?


Severity Code Description Project File Line Suppression State
Error C2676 binary '[': 'Student' does not define this operator or a conversion to a type acceptable to the predefined operator

 #include <iostream>
#include<string>
using namespace std;
struct Student
{
    int phoneNumber;
    string name;
};

int main()
{
    Student myStudent[10];
    int num; string name;
    for (int i = 0; i < 5; i++)
    {
        cout << "Name " << i + 1 << ":";
        getline(cin >> ws, myStudent[i].name);
        cout << "Phone Number " << i + 1 << " :";
        cin >> myStudent[i].phoneNumber;
    }
    for (int i = 0; i < 5; i++)
    {
        for (int j = i + 1; j < 5; j++)
        {
            if (myStudent[i].name > myStudent[j].name)
            {
                //swap(myStudent[i], myStudent[j]); It's OK.
                Student TStudent = myStudent[i]; // ERROR
                myStudent[i] = myStudent[j];
                myStudent[j] = myStudent;
            }
        }
    }
    for (int i = 0; i < 5; i++)
    {
        cout << "Name " << i + 1 << ": " << myStudent[i].name; cout << endl;
        cout << "Phone Number " << i + 1 << ": " << myStudent[i].phoneNumber;
    }
    return 0;
}

[Ganado]

Perhaps if you gave your variables better names, the issue might be more obvious.
You have an array of students called "myStudent" (singular).
You then create a variable called TStudent on line 28.
But then, on line 30, you attempt to assign myStudent (your array of students) to myStudent[j] (a Student).

You probably meant to assign TStudent.

[jonnin]

usually you want to set it up so you swap a pointer, not an object, for large numbers of items or large numbers of swaps (like sorting).

[Ganado]

You'd (generally) prefer pointers if it's large sizes of data per element. If each element in the array is relatively small, even if you have thousands of elements, you'd still prefer by-value swaps rather than dealing with pointers, since using pointers could cause tons of cache misses. (But in this case, since std::strings already have a pointer in them, I imagine the benefits either way are little. Just a guess, didn't measure.)

[jonnin]

I was not saying to make the data dynamic (that would indeed cause cache misses).
Keep the data in a solid block, as you said.