Data types Flashcards
Primitive Data Types
“The basic data types provided by a programming language as building blocks. Most languages allow more complicated composite types to be recursively construction starting from basic types. E.g. char, integer, float, Boolean. As an extension a ‘string’ data type is constructed behind the scenes of many char data types.”
Integer
“A data type used to store positive and negative whole numbers
Real
“A data type used to store an approximation of a real number in a way that can support a trade-off between range and precision. A number is, in general, represented approximately to a fixed number of significant digits and scaled using an exponent.”
Floating Point
“A data type used to store an approximation of a real number in a way that can support a trade-off between range and precision. A number is, in general, represented approximately to a fixed number of significant digits and scaled using an exponent.”
Character
“A single alphanumeric character or symbol.”
String
“A sequence of alphanumeric characters and or symbols. e.g. a word or sentence.”
Boolean
“Used to store the logical conditions TRUE / FALSE. Often translated to On/Off, Yes/No etc.”
Binary
“Binary describes a numbering scheme in which there are only two possible values for each digit: 0 and 1. The term in computing refers to any digital encoding system in which there are exactly two possible states. E.g. in memory, storage, processing and communications, the 0 and 1 values are sometimes called “low” and “high”, respectively.”
Sign and Magnitude
“A method in computing of being able to store negative numbers as string of pure binary digits. It works by turning the MSB into a sign bit, where 0 represents a positive number and 1 represents a negative.”
Two’s Complement
“A method in computing of being able to store and represent floating point real numbers (both positive and negative) as a string of pure binary digits. Uses the concepts of two’s complements, mantissa and exponent.”
Hexadecimal
“A numerical system of notation which uses 16 rather than 10 as its base. The 16 Hex base digits are 0-9 and the letters A-F.”
Denary
“A numerical system of notation which uses 10 as its base. The 10 Decimal base digits are 0-9.”
Floating Point Arithmetic
“The mathematical process of performing simply calculations on more than one floating-point number stored in binary notation.”
Bitwise Manipulation
“The act of algorithmically manipulating bits or other pieces of data shorter than a word. Programming tasks that require a bit manipulation include low-level device control, error detection and correction algorithms, data compression, encryption algorithms, and optimisation.”
Shifts
“An operation that moves the bits held in a register, called the shift register, either to the left or the right. There are three different types of shift: arithmetic shift, logical shift and cyclic shift. They are distinguished by what happens to the bits that are shifted out of the register at one end and what is moved in to fill the vacant space at the other end.”
AND
“A logical operator used within a program. AND works by only returning TRUE if both values being compared are TRUE.”
OR
“A logical operator used within a program. OR works by returning TRUE as long as either value being compared is TRUE.”
XOR
“A logical operator used within a program. XOR stands for exclusive OR. It will return TRUE if the two items being compared are different.”
Character Sets
“The set of symbols that may be represented in a computer at a particular time. These symbols, called characters, can be letters, digits, spaces or punctuations marks, the set includes control characters.”
ASCII
“America Standard Code for Information Interchange”
A character set devised for early telecommunication systems but proved to be ideal for computer systems. ASCII codes use 7-bits giving 32 control codes and 96 displayable characters (the 8th bit is often used for error checking).”
UNICODE
“Standard character set that replaces the need for all the different character sets. It incorporates characters from almost all the world’s languages. It is a 16-bit extension of ASCII.”
