What is the difference between , and + while concatenating?

Question

I have been coding with c# for a last couple of months now, but every time I concatenate I always get confused between the difference between the comma , and the pl

Answer 1

The comma is used as a separator while formatting strings, while the plus sign is used for normal concatenation.

Formatting is where you have placeholders such as {0} and {1}. Other strings, separated by commas, are used to fill these placeholders. Note that the commas are not operators and are simply used to separate parameters. This outputs Hello world!:

string greet = "Hello";
Console.WriteLine("{0}{1}", greet, " world!");

Concantenation is more straight forward. It simply combines the strings in order. Same example but with concatenation:

string greet = "Hello";
Console.WriteLine(greet + " world!");

Edit: now that you have included the specific problem, here's what you can try:

Console.WriteLine("Your id is: {0}" , id++);