Data Types Flashcards
What are the 5 primitive data types?
- integer
- real/floating point
- character
- string
- boolean
What is an integer?
- a whole number with no fractional/decimal parts
- Can be positive or negative
- useful for counting things
What is a real/floating point number?
- positive or negative number which can but don’t need a fractional part
- useful for measuring things
- all integers are real numbers
What is a character?
- a single symbol used by a computer
- Eg. The letters of the alphabet, numbers, special characters
What is a string?
- a collection of characters
- can store a single character or many characters in succession
- useful for storing text and phone numbers starting in 0 (normal integers or floating point would get rid of the starting 0)
What is a Boolean?
- values of this data type are restricted to True and False
- useful for storing data that can only take 2 values eg. the state of a power button
What is the human counting system?
Base 10 - denary
What is the computer counting system?
Base 2 - binary
A single binary digit is a …
Bit
8 binary digits combined is a …
Byte
4 binary digits combined is a …
Nybble
How do you convert from binary to denary?
- the least significant bit is the one furthest right
- The most significant bit is the one furthest left
- the value of the columns increase by a power of 2 each one you move further right
- if the column has a 1 in it counts the value of that column once, if there is a 0 don’t count it
- add the value of all the columns with a 1 in them to get the binary number in denary
How do you convert from denary to binary?
- find the largest power of 2 which is smaller than the number you are converting, the write out the binary place values up to this value
- subtract this value from the original value, then repeat the process until you have 0.
- Make sure all the binary bits with 1s add up to the original value
What are the binary addition rules?
0+0+0=1
0+0+1=1
0+1+1=10 (1 is carried to next column in column addition)
1+1+1=11 (1 is carried over to next column in column addition)
What are the binary addition rules?
0+0+0=1
0+0+1=1
0+1+1=10 (1 is carried to next column in column addition)
1+1+1=11 (1 is carried over to next column in column addition)
How would you represent a binary number as a whole number of bytes?
You would add leading 0’s (0’s in front of the actual number) - these don’t affect the value of the binary number
How do you do binary addition?
Do it like column addition - like up the 2 binary numbers in columns using 1s column to like them up and then apply binary addition rules
If there is a carry then put the carried one in small under the next column to the left
what are the basic binary subtraction rules?
0-0=1
1-0=1
1-1=0
0-1=1 (borrow 1 from the adjacent higher order digit)
how do you do basic binary subtraction?
do it like normal column subtraction following the rules of binary subtraction and doing carries where you need to
what sort of counting system is hexadecimal?
base 16
how do you represent values 10-15 using hexadecimal?
using letters A-F
A=10, B=11, C=12, D=13, E=14, F=15
How do you convert from hexadecimal into denary?
- use the place values of hex and multiply by the column place value
- each column has a place value to the power of 16, with powers increasing the further left you move along
how do you convert from denary to hex?
- divide the number by 16
- the remainder will be the rightmost hex value
- if there’s no remainder then rightmost digit will be 0
how do you convert from hex to binary?
- convert each hex digit to a denary digit and then convert this into a binary nybble (4 bits)
- then recombine all the nybbles in the right order to get the binary number