8.14 - Friends database, using files

Objetive

Expand the "friends database", so that it loads data from file at the beginning of each session (if the file exists) and saves the data to file when the session ends. Therefore, the data entered in a session must be available for the next session.

Solution

using System;
using System.IO;

public class FriendsDatabase
{   
struct people
{
public string name;
public string email;
public string address;
public ushort year;
}

public static void Main ()
{
int total = 275;
people[] p = new people[total];
int amount = 0;

char option;
bool found;
string textSearch;
string name = "friends.dat";

if (File.Exists(name))
{
StreamReader file = File.OpenText(name);
amount = Convert.ToInt32(file.ReadLine());

file.ReadLine();

for (int i = 0; i < amount; i++)
{
if (i < total)
{
p[i].name = file.ReadLine();
p[i].email = file.ReadLine();
p[i].address = file.ReadLine();
p[i].year = Convert.ToUInt16(file.ReadLine());
file.ReadLine();  
}
}
file.Close();
}

do
{
Console.WriteLine("1- Add data");
Console.WriteLine("2- Show");
Console.WriteLine("3- View all data");
Console.WriteLine("4- Show between dates");
Console.WriteLine("5- Show oldest");
Console.WriteLine("6- Show fields match");
Console.WriteLine("0- Exit");

Console.Write("Enter a option: ");
option = Convert.ToChar(Console.ReadLine());

switch(option)
{

case '1':
if (amount < total -1 )
{
do
{
Console.Write("Name: ");
p[amount].name = Console.ReadLine();

if (p[amount].name.Length > 40)
Console.WriteLine("Max 40 letters");
}
while(p[amount].name.Length > 40);

do
{
Console.Write("Email: ");
p[amount].email = Console.ReadLine();

if (p[amount].email.Length > 30)
Console.WriteLine("Max 30 letters");
}
while(p[amount].email.Length > 30);

do
{
Console.Write("Address: ");
p[amount].address = Console.ReadLine();

if (p[amount].address.Length > 150)
Console.WriteLine("Max 150 letters");
}
while(p[amount].address.Length>150);

do
{
Console.Write("Year: ");
p[amount].year = Convert.ToUInt16(Console.ReadLine());

if (p[amount].year < 1850 || p[amount].year > 2100)
Console.WriteLine("1850-2100");
}
while(p[amount].year < 1850 || p[amount].year > 2100);

amount++;
Console.WriteLine();
}
else
Console.WriteLine("Full");

break;

case '2':
if (amount == 0)
Console.WriteLine("No data");
else
{
for(int i = 0; i < amount; i++)
{
if(p[i].name.Length <= 30)
Console.WriteLine("{0}: Name = {1}", i + 1, p[i].name);
else
Console.WriteLine("{0}: Name = {1}", i + 1, 
p[i].name.Substring(0, 30) + "...");

if( i % 20 == 19)
Console.ReadLine();
}
}

break;
case '3':
Console.Write("Enter the person: ");
textSearch = Console.ReadLine();

found = false;
for(int i = 0; i < amount; i++)
{
if(textSearch.ToLower() == p[i].name.ToLower() )
{
found=true;
Console.WriteLine( "{0}: Year = {1}, Email = {2}, Address = {3}", i                  + 1, p[i].year, p[i].email, p[i].address);
}
}

if(!found)
Console.WriteLine("Not exists");

break;

case '4':
Console.Write("Enter the first year: ");
int year1 = Convert.ToUInt16(Console.ReadLine());

Console.Write("Enter the second year: ");
int year2 = Convert.ToUInt16(Console.ReadLine());


if(year1 > year2)
{
int aux = year2;
year2 = year1;
year1 = aux;
}

found = false;
for(int i = 0; i < amount; i++)
{
if(p[i].year >= year1 && p[i].year<=year2)
{
Console.Write(p[i].name + " - ");
found = true;
}
}

if(!found)
Console.WriteLine("Not found");
break;


case '5': 
if (amount == 0)
Console.WriteLine("No data");
else
{
int firstYear = p[0].year;
found = false;

for(int i = 1; i < amount; i++)
if(p[i].year < firstYear)
firstYear = p[i].year;

for(int i=0; i= 0)
{
Console.WriteLine( "{0}: Address = {2}, Year = {3}",
i + 1, p[i].name, p[i].address, p[i].year);

if( Console.ReadLine().ToLower() == "end")
break;
}
}
break;

case '0':
break;

default:
Console.WriteLine("Wrong option");
break;
}

}
while (option != '0');

StreamWriter dataFile = File.CreateText(name);
dataFile.WriteLine( amount );
dataFile.WriteLine();

for(int i = 0; i < amount; i++)
{
dataFile.WriteLine(p[i].name);
dataFile.WriteLine(p[i].email);
dataFile.WriteLine(p[i].address);
dataFile.WriteLine(p[i].year);
dataFile.WriteLine();
}

dataFile.Close();
}
}


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