how to add string in stringc# code example

Example 1: insert variables into string c#

string data = "Mr. Rogers";
var str = $"Hello {data}, how are you doing?";

Example 2: how to append something to a string in c#

string fName = "hello ";    
string lName = "world";    
string Name = string.Concat(fName, lName); 
//or
string firstName = "hello ";    
string lastName = "world";    
string name = firstName + " " + lastName;