A data type is a classification of data which tells the compiler or interpreter how the programmer intends to use the data. Most programming languages support various types of data, including integer, real, character or string, and Boolean.
Our interactions (inputs and outputs) with a program are treated in many languages as a stream of bytes. These bytes represent data that can be interpreted as representing values that we understand. Additionally, within a program, we process this data in various ways such as adding them up or sorting them. This data comes in different forms. Examples include:
A major part of understanding how to design and code programs is centered in understanding the types of data that we want to manipulate and how to manipulate that data.
Common data types include:
| Data Type | Represents | Examples |
|---|---|---|
| integer | whole numbers | -5,0,123 |
| floating point (real) | fractional numbers | -87.5,0.0,3.14159 |
| string | A sequence of characters | "Hello world!" |
| Boolean | logical true or false | true,false |
| nothing | no data | null |
The common data types usually exist in most programming languages and act or behave similarly from language to language. Additional complex and/or composite data types may exist and vary from language to language.
Function Main ... This program demonstrates variables, literal constants, and data types. Declare Integer i Declare Real r Declare String s Declare Boolean b Assign i = 1234567890 Assign r = 1.23456789012345 Assign s = "string" Assign b = true Output "Integer i = " & i Output "Real r = " & r Output "String s = " & s Output "Boolean b = " & bEnd
Integer i = 1234567890Real r = 1.23456789012345String s = stringBoolean b = true
