public static void Run()
{
string filePath = @".\Resources\Pop by Largest Final.csv";
CsvReaderWithList reader = new CsvReaderWithList(filePath);
List <Country> countries = reader.ReadAllCountries();
foreach (Country country in countries.OrderBy(x => x.Name))
{
Console.WriteLine($"{PopulationFormatter.FormatPopulation(country.Population).PadLeft(15)}: {country.Name}");
}
//intead of printing all values at once.batching countries up would be nice
//but, LINQ doesn't support batching. use forloop for batching
Console.WriteLine("------------------------------------------------------------------");
// listing the first 20 countries without commas in their names
var filteredCountries = countries.Where(x => !x.Name.Contains(',')).Take(20);
//OR
var filteredCountries2 = from country in countries
where !country.Name.Contains(",")
select country;
//unlike LINQ method syntax, query syntax don't suppoert all LINQ features(ex: Take(20))
foreach (Country country in filteredCountries)
{
Console.WriteLine($"{PopulationFormatter.FormatPopulation(country.Population).PadLeft(15)}: {country.Name}");
}
//WHERE >it only filters data but it won't remove it physically at an index.LINQ is read-only
Console.WriteLine();
Console.WriteLine("------------------------------------------------------------------");
// listing the 10 highest population countries in alphabetical order.
// Reverse Where() and Take() to see the impact of swapping chaining order round
foreach (Country country in countries.Take(10).OrderBy(x => x.Name))
{
Console.WriteLine($"{PopulationFormatter.FormatPopulation(country.Population).PadLeft(15)}: {country.Name}");
}
//here think 'countries' as datasorce instead of collection.
//to LINQ, contries collection is just something that can be enumerated.
//Most collections implement IEnumerable<T>
//IEnumerable<T> exposes the ability to supply objects on demand.LINQ methods can leverage that interface.
//for LINQ, 'countries' is just datasource.it wont care about it is collectio. or not.
//how it can use orderby without knowing List<T> is a collection?
//Take is from Enumerable class inside system.Linq Namespace.so, it works with any objects that implement 'IEnumerable<T>'.
//almost all collections implement IEnumerable<T>, LINQ works for all collections
//FOR LOOP is for ARRAY & LIST. (not dictionary, as it don't have an index)
//LINQ works with ARRAY , LIST & DICTIONARY
}
public static void Run()
{
List <int> ints = new List <int>(); //List<T> always starts with empty.it don't have a special constructor.
//int[] ints = new int[10];//Arrays instantiated with special sytax [], as it part of .net Runtime
//Lists are not part of .Net Runtime.so,normal syntax for new objects
List <string> daysOfWeek = new List <string>
{
"Monday",
"Tuesday",
"Wednesday",
"Thursday",
"Friday",
"Saturday",
"Sunday"
}; //unlike array,here Under the hood the compilar turns collection initalizer{} to .Add("day") method like below.
List <string> daysOfWeek1 = new List <string>();
daysOfWeek1.Add("Monday");
daysOfWeek1.Add("Tuesday");
daysOfWeek1.Add("Wednesday");
daysOfWeek1.Add("Thursday");
//---------------List<T> ---------
//T is a generic type.Generic type applies to all the collections in C# except Arrays.
//Arrays can't be generic.
//T[] generic=new T[10];//invalid
//--------------------------
string filePath = @".\Resources\Pop by Largest Final.csv";
CsvReaderWithList reader = new CsvReaderWithList(filePath);
List <Country> countries = reader.ReadAllCountries();
// This is the code that inserts and then subsequently removes Lilliput.
// Comment out the RemoveAt to see the list with Lilliput in it.
Country lilliput = new Country("Lilliput", "LIL", "Somewhere", 2_000_000);
int lilliputIndex = countries.FindIndex(x => x.Population < 2_000_000);
countries.Insert(lilliputIndex, lilliput);
Console.WriteLine("-----------" + lilliputIndex + "---" + lilliput.Name + "------------");
countries.RemoveAt(lilliputIndex);
//INSERT * REMOVE from list casuses to shift all the data after index which reduces performance.careful
foreach (Country country in countries)
{
Console.WriteLine($"{PopulationFormatter.FormatPopulation(country.Population).PadLeft(15)}: {country.Name}");
}
Console.WriteLine($"{countries.Count} countries");
//finding item by code
int index = countries.FindIndex(x => x.Code == "USA");
Country selectedCountry = countries[index];
Console.WriteLine("---------SelectedCountry: " + JsonConvert.SerializeObject(selectedCountry));
//OR
//USE DICTIONARY //prefer
//---------------MANIPULATING LIST DATA-------------------------
//foreach is simple but it has no control.
//for loop give finer control for LISTS AND ARRAYS.difficult for DICTIONARIES.
string filePath1 = @".\Resources\Pop by Largest Final.csv";
CsvReaderWithList reader1 = new CsvReaderWithList(filePath1);
List <Country> countries1 = reader.ReadAllCountries();
// comment this out to see all countries, without removing the ones with commas
reader1.RemoveCommaCountries(countries1);
Console.Write("Enter no. of countries to display> ");
bool inputIsInt = int.TryParse(Console.ReadLine(), out int userInput);
if (!inputIsInt || userInput <= 0)
{
Console.WriteLine("You must type in a +ve integer. Exiting");
return;
}
//int maxToDisplay = Math.Min(userInput, countries.Count);
int maxToDisplay = userInput;
//display from start
for (int i = 0; i < countries.Count; i++)
{
if (i > 0 && (i % maxToDisplay == 0))
{
Console.WriteLine("Hit return to continue, anything else to quit>");
if (Console.ReadLine() != "")
{
break;
}
}
Country country = countries[i];
Console.WriteLine($"{i + 1}: {PopulationFormatter.FormatPopulation(country.Population).PadLeft(15)}: {country.Name}");
}
//display from end
for (int i = countries.Count - 1; i >= 0; i--)
{
int displayIndex = countries.Count - 1 - i;
if (displayIndex > 0 && (displayIndex % maxToDisplay == 0))
{
Console.WriteLine("Hit return to continue, anything else to quit>");
if (Console.ReadLine() != "")
{
break;
}
}
Country country = countries[i];
Console.WriteLine($"{displayIndex + 1}: {PopulationFormatter.FormatPopulation(country.Population).PadLeft(15)}: {country.Name}");
}
}