var str = new TheBestStructEver(5);

Console.WriteLine(str.A);

public struct TheBestStructEver
{
    public int A;

    public TheBestStructEver(int a)
    {
        A = a;
        this = new TheBestStructEver();
    }
}

IL_0013: ldarg.0
IL_0014: initobj      TheBestStructEver

string filename1 = @"c:\documents\files\u0066.txt";
string filename2 = "c:\\documents\\files\\u0066.txt";

Console.WriteLine(filename1);
Console.WriteLine(filename2);

//     c:\documents\files\u0066.txt
//     c:\documents\files\u0066.txt

string s1 = "He said, \"This is the last \u0063hance\x0021\"";
string s2 = @"He said, ""This is the last \u0063hance\x0021""";

Console.WriteLine(s1);
Console.WriteLine(s2);

//     He said, "This is the last chance!"
//     He said, "This is the last \u0063hance\x0021"

string[] @for = { "John", "James", "Joan", "Jamie" };
for (int ctr = 0; ctr < @for.Length; ctr++)
{
   Console.WriteLine($"Here is your gift, {@for[ctr]}!");
}

//     Here is your gift, John!
//     Here is your gift, James!
//     Here is your gift, Joan!
//     Here is your gift, Jamie!

int[] nums1 = { 1, 2, 3, 4 };
int[] nums2 = new int[] { };   // пустой массив

int[] nums1 = [ 1, 2, 3, 4 ];
int[] nums2 = [];   // пустой массив

List<int> list1 = [1, 2, 3, 4];
List<int> list2 = []; //  пустой список
Span<int> span1 = [1, 2, 3, 4];

var tom = new Person("Tom", 38);
Console.WriteLine(tom);
 
public class Person(string name, int age)
{
    public Person(string name) : this(name, 18) { }
    public string Name => name;
    public int Age => age;
 
    public override string ToString() => $"name: {name}, age: {age}";
}

public Person(string name) : this(name, 18) { }