Operators apply simple operations such as addition and multiplication to operands such as numbers. They usually return a new value that is the result of the operation.
Most operators are binary, meaning that they work on two operands, as shown in the following pseudocode:
var resultOfOperation = FirstOperand operator SecondOperand;
Some operators are unary, meaning they work on a single operand.
A ternary operator works on three operands.
Two common unary operators are used to increment ++ and decrement -- a number.
In Visual Studio 2017, from the View menu, choose Other Windows, and then C# Interactive.
Enter the following code:
> int i = 3; > i 3
Note that when you enter a full statement ending in a semicolon, it is executed when you press Enter.
The first statement uses the assignment operator = to assign the value 3 to the variable i. When you enter a variable name at the prompt, it returns the variable's current value.
Enter the following statements, and before pressing Enter, try to guess what the value of x and y will be:
> int x = 3; > int y = x++;
Now check the values of x and y. You might be surprised to see that y has the value 3:
> x 4 > y 3
The variable y has the value 3 because the ++ operator executes after the assignment. This is known as postfix. If you need to increment before assignment, use prefix, as shown in the following code:
> int x = 3; > int y = ++x; > x 4 > y 4
You can decrement the value using the -- operator.
Tip
Good Practice
Due to the confusion between prefix and postfix for the increment and decrement operators when combined with assignment, the Swift programming language designers plan to drop support for this operator in version 3. My recommendation for usage in C# is to never combine the use of ++ and -- operators with an assignment =. Perform the operations as separate statements.
Arithmetic operators allow you to perform arithmetic operations on numbers.
Enter the following in the C# Interactive window:
> 11 + 3 14 > 11 - 3 8 > 11 * 3 33 > 11 / 3 3 > 11 % 3 2 > 11.0 / 3 3.6666666666666665
To understand the divide (/) and modulus (%) operators when applied to integers (whole numbers), you need to think back to primary school.
Imagine you have eleven sweets and three friends. How can you divide the sweets between your friends? You can give three sweets to each of your friends and there will be two left over. Those two are the modulus, also known as remainder. If you have twelve sweets, then each friend gets four of them and there are none left over. So, the remainder is 0.
If you start with a real number, such as 11.0, then the divide operator returns a floating point value, such as 3.6666666666665, rather than a whole number.