C# Tutorial · C# Basics · Lesson 6 of 22
C# Operators and Math
Arithmetic, comparison, logical, null operators and the Math class.
Operators
int a = 17, b = 5;
Console.WriteLine($"{a + b} {a - b} {a * b} {a / b} {a % b}");
Console.WriteLine(a > b && b > 0);
string s1 = "hi", s2 = string.Concat("h", "i");
Console.WriteLine(s1 == s2);
string? nickname = null;
Console.WriteLine(nickname ?? "Anonymous");
Console.WriteLine(nickname?.Length is null); // ?. gave null instead of throwing
nickname ??= "Guest";
Console.WriteLine(nickname);
Console.WriteLine(a % 2 == 0 ? "even" : "odd");
Output
22 12 85 3 2 True True Anonymous True Guest odd
Run this on your computer — see “Get Started” for setup.
==on strings compares contents in C# (unlike Java).??gives a default fornull;?.safely accesses members of a possibly-null object;??=assigns when null.- The ternary
cond ? a : bpicks a value.
Math
Console.WriteLine(Math.Max(4, 9) + " " + Math.Min(4, 9));
Console.WriteLine(Math.Sqrt(144) + " " + Math.Pow(2, 10) + " " + Math.Abs(-7));
Console.WriteLine(Math.Round(2.5) + " " + Math.Round(3.5) + " " + Math.Round(2.5, MidpointRounding.AwayFromZero));
Console.WriteLine(Math.Floor(2.7) + " " + Math.Ceiling(2.1));
Console.WriteLine(Math.Round(Math.PI, 4));
Output
9 4 12 1024 7 2 4 3 2 3 3.1416
Run this on your computer — see “Get Started” for setup.
Test yourself
What does null ?? "x" return?
null"x"An exception""
Show answer
Answer: "x"