ages.cpp


// ages.cpp

#include <iostream.h>
#include <apstring.h>
#include <apvector.h>
#include <fstream.h>
#include <stdlib.h>

// global definitions

struct student
{
	apstring lastName;
	apstring firstName;
	int age;
};

struct listType
{
	int number;		// how many Students are in the list
	apvector <student> list;
};

// function prototypes

void loadFile (const apstring &, listType &);
void printList (const listType &);
void addStudent (listType &, const student &);
void doAddStudent (listType &);
void swap (student &, student &);
void quickSort (apvector<student> &, int, int);
void saveFile (const apstring &, const listType &);
ostream& operator<< (ostream& out, const student &);

main()
{
	listType data;
	
	loadFile ("Mac HD:ap97:names.txt", data);
	printList (data);
	doAddStudent (data);
	quickSort (data.list,0,data.number-1);
	cout << endl;
	printList (data);
	saveFile ("Mac HD:ap97:names.txt", data);
	return 0;
}

 void loadFile (const apstring &fileName, listType &temp)
// precondition:  temp.list has a size of 0, will need to be resized
{
	char*  fn = fileName.c_str();		// convert apstring to c-style string
	ifstream  inFile;		// open inFile, link to external file

	inFile.open(fn);
	if (inFile.fail())
	{
		cerr << "Could not open " << fileName << endl;
		abort();
	}	
	inFile >> temp.number;
	temp.list.resize(temp.number);	
	for (int k=0; k<temp.number; k++)
	{
		inFile >> temp.list[k].lastName;
		inFile >> temp.list[k].firstName;
		inFile >> temp.list[k].age;
	}
}

void printList (const listType &temp)
{
	cout << endl;
	for (int k=0; k<temp.number; k++)
		cout << k+1 << " " << temp.list[k] << endl;
	cout << endl;
}

void doAddStudent (listType &temp)
{
	student newData;
	do
	{
		cout << "Enter last name of Student (done to quit) ---> ";
		cin >> newData.lastName;
		if ("done" != newData.lastName)
		{
			cout << "Enter first name of Student ---> ";
			cin >> newData.firstName;
			cin.get();	// to dump return key stuck in cin
			cout << "Enter age of Student ---> ";
			cin >> newData.age;
			addStudent (temp,newData);
		}
	}
	while ("done" != newData.lastName);
}

void addStudent (listType &temp, const student &newStudent)
{
	if (temp.list.length() == temp.number)		// if list is full
		temp.list.resize (temp.number*2);		// make list twice as big
	temp.list[temp.number] = newStudent;	   // copy newStudent into list
	temp.number++;
}

void  swap (student &a,  student &b)
{
	student temp = a;  
	a = b;  
	b = temp;
}

void quickSort (apvector<student> &list, int first, int last)
{
	int g = first, h = last;
	int midIndex;
	apstring dividingValue;

	midIndex = (first + last) / 2;
	dividingValue = list[midIndex].lastName;
	do
	{
		while (list[g].lastName < dividingValue) g++;
		while (list[h].lastName > dividingValue) h--;
		if (g <= h)
		{
			swap(list[g], list[h]);
			g++;
			h--;
		}
	}
	while (h > g);
	if (h > first) quickSort (list,first,h);
	if (g < last) quickSort (list,g,last);
}

void saveFile (const apstring &fileName, const listType &temp)
{
	char* fn = fileName.c_str();
	ofstream outFile (fn);
	
	outFile << temp.number << endl;
	for (int k=0; k<temp.number; k++)
		outFile << temp.list[k] << endl;
}

ostream& operator<< (ostream& out, const student &temp)
{
	out << temp.lastName << " " << temp.firstName << " " << temp.age;
	return out;
}