4. Data representation and data types

Question 1

What is a character set?

Answer 1

A defined list of characters recognized by the computer’s hardware and software, with each character being represented by a number. They are agreed standards for referring to all the characters a computer can use.

Question 2

What is ASCII?

Answer 2

A 7-bit character set that has space for 128 symbols, enough for standard English. The codes are stored by computers as 8 bits with the MSB set to 0.

Question 3

What is extended ASCII?

Answer 3

An 8-bit character set that provides extra characters for foreign languages and graphic symbols.

Question 4

What is Unicode?

Answer 4

A 24-bit character set that has characters from every written language, historic symbols and emojis. Hexadecimal is often used instead of binary as writing 24 bits is slow and cumbersome.

Question 5

How many bits are needed to store a single character?

Answer 5

8 bits (ASCII)
16 bits (Unicode)

Question 6

How many bits are needed to store a string?

Answer 6

8 bits per character (ASCII)
16 bits per character (Unicode)

Question 7

How many bits are needed to store an unsigned/signed integer?

Answer 7

16 bits (short integer)
64 bits (long integer)

Question 8

How many bits are needed to store a boolean?

Answer 8

1 bit

Question 9

What are the advantages of using standardized character sets?

Answer 9

• ensures all computers use the same character representation
• Unicode allows storage of complex characters such as Chinese symbols
• Unicode can represent a larger range of characters than ASCII