C# Arrray Methods for Daily Use

//Q1. Convert Array into string
string[] animals = { "Rat", "Cat", "Dog", "Fox", "Lion" };
string a2s = String.Join(",", animals);
Console.WriteLine(a2s);

//Q2. Convert string into Array
string quote = "It is not a lack of love, but a lack of friendship that makes unhappy marriages.";
char delimiter = ' ';
string[] s2a = quote.Split(delimiter);
foreach (var q in s2a)
{
    Console.WriteLine(q);
}

//Q3. Convert string type number into number
string intNum = "123";
string dblNum = "123.45";
int num = Convert.ToInt32(intNum);
double dbl = Convert.ToDouble(dblNum);
Console.WriteLine(num);
Console.WriteLine(dbl);

//Q4. Convert string type date into DateTime date
string date_str = "11/11/2021";
DateTime date = Convert.ToDateTime(date_str);
Console.WriteLine(date.ToString("D"));

//Q5. String comparison
string city = "London";
Console.WriteLine(city.Equals("london"));//False
Console.WriteLine(city == "london");//False
Console.WriteLine(city.Equals("London"));//True
Console.WriteLine(city == "London");//True
Console.WriteLine(city.Equals("london", StringComparison.CurrentCultureIgnoreCase));//True

//Q6. Search an array element
string[] animates = { "Rat", "Cat", "Snake", "Dog", "Fox", "Lion", "Tiger", "Bear", "Bull", "Cow", "Rhino" };
var result = Array.Find(animates, s => s == "dog"); //2nd arg is System.Predicate<String>, case senstive
if (result == null)
{
    Console.WriteLine("Dog not found.");
}
else
{
    Console.WriteLine(result);
}

//Q7. Search an array element
// Find first animal which names begin with C
var r1 = Array.Find(animates, s => s.StartsWith("C"));
Console.WriteLine(r1);//Cat
// Find last animal which names begin with C
var r2 = Array.FindLast(animates, s => s.StartsWith("C"));
Console.WriteLine(r2);//Cow

//Q8. Find all animals which names begin with C
var allRes = Array.FindAll(animates, s => s.StartsWith("R"));
foreach (var r in allRes)
{
    Console.WriteLine(r);
}

//Q9. Sort Array
Array.Sort(animates); //Sort returns void type
foreach (var a in animates)
{
    Console.Write("{0} < ", a);
}

//Q10. Reverse Array
Array.Reverse(animates);
Console.WriteLine();
for (int i = 0; i < animates.Length; i++)
{
    Console.Write("{0} > ", animates[i]);
}

//Q11. Get distinct array elements
Console.WriteLine();
string[] myarr = { "Bear", "Bull", "Cow", "Rhino", "Bear", "Ox" };
//we use LINQ to get the result, so use System.Linq namespace
var distinct = myarr.Distinct();
foreach (var item in distinct)
{
    Console.Write("{0} ", item);
}