Ejercicio
Base de datos de amigos, utilizando archivos
Objetivo
Expanda la "base de datos de amigos", de modo que cargue los datos del archivo al comienzo de cada sesión (si el archivo existe) y guarde los datos en el archivo cuando finalice la sesión. Por lo tanto, los datos introducidos en una sesión deben estar disponibles para la siguiente sesión.
Código de Ejemplo
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 < amount; i++)
{
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();
}
}