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AS 1.4.1 - Data Types


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primitive data type
a data type which is provided by a programming language
integer
a whole number (positive or negative), e.g. -25, 0, 3, 287
float
a number with a fractional part / a decimal number, e.g. 1.0, 15.5, -2.333
Boolean
this variable can only take the value TRUE or FALSE
character
a singular letter, number or special character (typically represented in ASCII), e.g. a, A, 8, %
string
a sequence of characters (including text, numbers, symbols, carriage returns and spaces), enclosed in quotation marks
denary
base 10 number system (ie. uses numbers 0-9)
binary
base 2 number system (ie. uses 0s and 1s)
hexadecimal
base 16 number system (ie. uses numbers 0-9 and letters A-F)
characters
Reasons for using Hexadecimal - Compared to binary, more bytes and information can be represented in fewer...
remember
Reasons for using Hexadecimal - Fewer human errors are likely to be made compared to using binary, as hex numbers are easier to write and...
bit
short for binary digit; has a single binary value (either a 0 or 1)
byte
a group of 8 bits
kibibyte
1024 bytes
mebibyte
1024 kibibytes
gibibyte
1024 mebibytes
Sign and Magnitude
a method to represent negative numbers in binary, but can then pose issues later when using the binary numbers in arithmetic
Two's Complement
a method to represent negative numbers in binary by switching all ones to zeros and all zeros to ones and then adding one to the result
character set
the mapping of a collection of characters to its unique bit sequence/code
American Standard Code for Information Interchange
the previous character set used, which used 7 bit codes for each character
Extended ASCII
the 8 bit character set that was developed from the 7 bit character set used beforehand, allowing for more characters to be stored and used
Unicode
the character set with 16 bit codes introduced to allow for the alphabets of all languages, making documents of different languages compatible
128
the number of combinations ASCII allowed for, which was very limited, thus prompting the introduction of Unicode which allowed for more characters to be stored
UTF-16
16 bit Unicode, allowing for 65,536 different combinations
UTF-32
32 bit Unicode, allowing for over 1 million combinations, thus being suitable to store most of the Chinese and Japanese alphabets as well