C++ Primer 7.8

7.8.cpp

#include <iostream>
using namespace std;

const int SLEN = 30;
struct student {
  char fullname[SLEN];
  char hobby[SLEN];
  int ooplevel;
};

// getinfo() has two arguments: a pointer to the first element of
// an array of student structures and an int representing the
// number of elements of the array.  The function solicits and
// stores data about students.  It terminates input upon filling
// the array or upon encountering a blank line for the student
// name.  The function returns the actual number of array elements
// filled.
int getinfo(student pa[], int n);

// display1() takes a student structure as an argument
// and displays its contents
void display1(student st);

// display2() takes the address of student structure as an
// argument and displays the structure's contents
void display2(const student * ps);

// display3() takes the address of the first element of an array
// of student structures and the number of array elements as
// arguments and displays the contents of the structures
void display3(const student pa[], int n);

int main()
{
  cout << "Enter class size: ";
  int class_size;
  cin >> class_size;
  while (cin.get() != '\n')
    continue;
  student * ptr_stu = new student[class_size];
  int entered = getinfo(ptr_stu, class_size);
  for (int i = 0; i < entered; i++) {
    display1(ptr_stu[i]);
    display2(&ptr_stu[i]);
  }
  display3(ptr_stu, entered);
  delete [] ptr_stu;
  cout << "Done\n";

  return 0;
}

int getinfo(student pa[], int n)
{
  int i = 0;
  for (; i < n; i++) {
    cout << endl;
    cout << "Please enter the student's name: ";
    cin.getline(pa[i].fullname, SLEN);
    if ('\0' == pa[i].fullname) {
      cout << "Error: no information." << endl;

      return i;
    }
    cout << "Please enter the student's hobby: ";
    cin.getline(pa[i].hobby, SLEN);
    cout << "Please enter the student's OOP (Object Oriented Programming) level: ";
    cin >> pa[i].ooplevel;
    if (cin.fail()) {
      cout << "Error: bad information (you have to input integer here)." << endl;

      // return i;
      cin.clear();
      while (cin.get() != '\n') { continue; }
      continue;
    }
    while (cin.get() != '\n') { continue; }
  }

  return i;
}

void display1(student st)
{
  cout << endl;
  cout << "name @ display1: " << st.fullname << endl;
  cout << "hobby @ display1: " << st.hobby << endl;
  cout << "OOP level @ display1: " << st.ooplevel << endl;
}

void display2(const student * ps)
{
  cout << endl;
  cout << "name @ display2: " << ps->fullname << endl;
  cout << "hobby @ display2: : " << ps->hobby << endl;
  cout << "OOP level @ display2: " << ps->ooplevel << endl;
}

void display3(const student pa[], int n)
{
  cout << endl;
  for (int i = 0; i < n; i ++) {
    cout << "name @ display3: " << pa[i].fullname << endl;
    cout << "hobby @ display3: " << pa[i].hobby << endl;
    cout << "OOP level @ display3: " << pa[i].ooplevel << endl;
  }
}