what is the meaning of : {0}

Question

what is the use of {0} after the word hello if i wanted the program to print hello + username

Answer 1

string world = "world!";

Console.WriteLine("Hello {0}", world);
// This is the same as
Console.WriteLine("Hello " + world);

I use the {x} only because it looks more, well, nice.

Answer 2

{x} is a place holder, which will be substituted by the variable during execution.

Answer 3

its uses to get index from user input values {0} here 0 is index of user input .

Answer 4

it is place holder