2.3 Characters Flashcards
How are characters represented and stored in binary?
Each character is represented by a binary value
Do uppercase characters have different values from lowercase characters?
Yes, even punctuation symbols have their own character code
How many characters are there on a standard keyboard?
- 26 lowercase letters
- 25 uppercase letters
- 10 numbers
- around 36 other characters
which all sum up to around 98 characters
How many bits would you need to represent the combinations of each character?
7 bits which can store up to 128 different combinations (aka 128 different characters)
What are character sets?
A set of letters, symbols and digits that can be represented by a computer
What are the 2 major character sets in use today?
ASCII, Unicode
What is ASCII
American Standard Code for Information Interchange has become the standard code used worldwide
What was ASCII developed for and when?
In the 1960’s representing the English alphabet
How many characters can ASCII encode?
128 (7 bits) characters
What are the characters used in ASCII?
- numbers 0-9
- Upper and lower case characters from a-z
- Punctuation symbols
- Space character
In the ASCII set, why is the character ‘7’ not the same in the binary value for ‘7’?
ASCII is a character set, which is used to represent language, whereas the binary number 7 is an integer which is represented in programming
ASCII groups and sequences
Characters are commonly grouped and run in sequence
- Numeric characters run 0-9 run consecutively from 48-57 on the ASCII table
A-Z characters are from 65-90
a-z characters are from 97-122
What are the differences between 7 bit and 8 bit ASCII?
7 bit ASCII has 128 different characters that can be encoded
8 bit ASCII can have up to 256 different characters that can be encoded
Can you do arithmetic with characters?
No
What is called when changing a data type from ASCII to binary in a program?
Casting
