More on Operations
Operation
Computer Science, and therefore programming, has its roots in mathematics and uses a lot technical terms and jargon from math. Unfortunately this means that most programmers need to be familiar with some of this jargon.
An operation is a fancy math term for “do something”, but carries with it its own set of vocabulary. An operation is composed of:
- an operator (one or more symbols)
- operands (one or more pieces of data)
- a semantic meaning (i.e. what the operator does)
Binary Operations
Binary operations operate on two inputs. This class of operations should be familiar from arithmetic. Its format is
operand1 operator operand2
2 + 4
x + ywhere the operator is typically some type of symbol.
Note that in this case the term binary refers to the fact that the operation is performed on exactly 2 operands, and not that the data is stored in a base-2 (binary) data format.
This can lead to some confusion among programmers when referring to bitwise operators, which are operators that perform actions on individual bits in a piece of data. Many programmers mistakenly call these “binary” operators since they operate on data at the binary level, but the proper term is “bitwise” opeartors.
Operator symbols are typically overloaded in programming languages, which means that they can do different things based on the types of the operands. For example, a typical language might do any of the following operations when the plus sign + is used as the operator, depending on the types of the individual operands:
| Type Operand 1 | Type Operand 2 | Result Type |
|---|---|---|
| int 2 |
int 4 |
int 6 |
| int 2 |
float 4.0 |
float 6.0 |
| float 1.1 |
float 3.7 |
float 4.8 |
| String “2” |
String “4” |
String “24” |
| String “2” |
int 4 |
Error operation not defined for an operand of type String and int |
We will have to refer to our language’s documentation for how each operator functions. Operator behavior, particularly in the presence of mixed-type operands varies from language to language.
The form operand1 operator operand2 is called infix notation. However, there is another construct called prefix, that looks like operator operand1 operand2 or + 2 4. For technical reasons it is easier to write programming languages that use prefix notation. In OOP, we may see prefix notations used for methods and classes, which were adapted from a functional programming language where prefix notation is more common.
Unary Operations
There are some operations that have just one operand, these are called unary operations. The typical form is operator operand or operand operator. A fairly common unary operator is ! for the logical operation “not”. !True is the same as False. We’ll introduce more of these operators in a later chapter.