title: Operators —

Operators

So far, we’ve looked at a few types of variables: int, float, string, and bool.

So, what are some things we might want to do with these types? Well, for numbers, we might want to add, subtract, multiply, or divide them.

After all, computers are great at math!

Math Operators For Numbers (And Strings)

Math operators include:
Addition (+)
Subtraction (-)
Multiplication (*)
Division (/)

Here’s a C# program that adds several int variables together representing the number of animals of various types, and stores them in a new int called NumAnimalsTotal

using System;

int NumCats = 5;
int NumDogs = 10;
int NumFerrets = 2;
int NumAnimalsTotal = NumCats + NumDogs + NumFerrets;

Here’s another C# program that calculates how much you might spend on coffee in a year. This one is a little more sophisticated, because it’s working with both int and float values, and multiplying them together:

using System;


int NumCoffeesPerMonth = 10;
float CostPerCoffee = 3.61f;
float Total = NumCoffeesPerMonth * CostPerCoffee * 12;
Console.WriteLine("You'll spend" + Total + " on coffee every year");

Also, take a look at that last line: We are adding a string value to an int value, to another string value. The computer knows how to convert number values into strings, so the result is just one longer string.

Relational Operators

You can also use “relational” operators such as: > (greater than), < (less than), >= (greater than or equal), <= (less than or equal), == (equals), and != (not equals). When you compare two numbers with a relational operators, the result is a bool value.

Examples:

using System;


bool oldEnoughToDrive = age >= 16;
...
string answer = Console.Readline();
bool answerIsYes = answer=="yes";

Operator Order:

Just like in math, operators are used in a particular order. We won’t go over all the details here, but one thing you should know is that youy can use parenthesis to control the order operators will be evaluated.

Examples:

//Add C+D first, then multiply by B:
float A = B*(C+D);

//Multiply B*C, then add D:
float A = (B*C)+D;

Boolean Operators

bool values have their own speical operators, which are used to combine bool values in logical ways. We will cover boolean operators in a later lesson when we talk about Control Flow!