Chapter 9 // Exercise 2 - Principles & Practice Using C++

In this exercise I am using Visual Studio Community 2017 and the header file "std_lib_facilities.h" which can be found here:

http://www.stroustrup.com/Programming/PPP2code/std_lib_facilities.h

Chapter 9 // Exercise 1

Design and implement a Name_pairs class holding (name, age) pairs where name is a string and age is a double. Represent that as a vector<string>  (called name) and a vector<double> (called age) member. Provide an input operation read_names() that reads a series of names. Provide a read_ages() operation that prompts the user for an age for each name. Provide a print() operation that prints out the (name[i], age[i]) pairs (one per line) in the order determined by the name vector. Provide a sort() operation that sorts the name vector in alphabetical order and reorganises the age vector to match. Implement all "operations" as member functions.

#include "stdafx.h"
#include "std_lib_facilities.h"

class Name_pairs
{
private:
 vector<string> name;
 vector<double> age;
public:
 void read_names(int iterator); //read in a series of names
 void read_ages();  //read in age for name
 void print();   //print out vectors
 void sortNP();   //sort the vectors alphabetically by name
};

void Name_pairs::read_names(int iterator)
{
 string names;
 for (int i = 0; i < iterator; ++i)
 {
  cout << "Name: ";
  cin >> names;
  name.push_back(names);
  cout << endl;
 }
}

void Name_pairs::read_ages()
{
 double ages;
 for (int i = 0; i < name.size(); ++i)
 {
  cout << "Age for " << name[i] << ": ";
  cin >> ages;
  age.push_back(ages);
  cout << endl;
 }
}

void Name_pairs::print()
{
 cout << endl;
 for (int i = 0; i < name.size(); ++i)
  cout << "Name: " << name[i] << "     Age: " << age[i] << endl;
}

void Name_pairs::sortNP()
{
 vector<string> name_copy = name;
 vector<double> age_copy = age;

 sort(name.begin(), name.end());  //sort actual names

 //go through each member of sorted name
 for (int i = 0; i < name.size(); ++i)
 {
  //go through each member of original copy name
  for (int j = 0; j < name.size(); ++j)
  {
   //if sorted name matches original
   if (name[i] == name_copy[j])
   {
    //assign original age to new position to match sorted vector
    age[i] = age_copy[j];
   }
  }
 }
}

int main()
{
 cout << "How many names to read in? > ";
 int howMany;
 cin >> howMany;

 Name_pairs namePair;

 //read in names
 namePair.read_names(howMany);

 //read in ages
 namePair.read_ages();

 //print
 namePair.print();

 //sort namePair alphabetically
 namePair.sortNP();

 //print
 namePair.print();

 keep_window_open();

 return 0;
}

This was basically chapter 8 exercise 7 but in a class form, so I just reused some of the functions from that and stuck it into a class.