Basic class

#include <iostream>
#include <iomanip>
#include <string>
#include <vector>

using namespace std::literals::string_literals;

class rollno {
private:
  std::string name_;
  uint32_t nr_;

public:
  rollno(std::string const & name = ""s, uint32_t nr = 0u) : name_ { name }, nr_ { nr } {}
  rollno(rollno const & that) = default;
  rollno(rollno && that) = default;
  ~rollno() = default;
  rollno & operator=(rollno const & that) = default;
  rollno & operator=(rollno && that) = default;

  std::string name(void) const { return name_; }
  std::string name(std::string const & name) { name_ = name; return name_; }
  unsigned nr(void) const { return nr_; }
  unsigned nr(uint32_t nr) { nr_ = nr; return nr_; }
};

int main() {
  auto roll = std::vector<rollno> {
    { "Rohit"s, 3u, },
    { "Priya"s, 4u, },
    { "Sneha"s, 5u, },
  };

  auto rt1 = rollno("Nish"s, 10u);
  roll.push_back(rt1);
  rt1.name("Mehrdad"s);
  rt1.nr(11u);
  roll.push_back(rt1);

  std::cout << "Student rollcall is:\n"s;
  for (rollno & rn : roll) {
    std::cout << std::setw(10) << rn.name()
              << std::setw(3) << rn.nr()
              << '\n';
  }

  return 0;
}