Notes-for-CAIE

2.2 Data representation

2.2.1 Data types

• select appropriate data types for a problem solution
• use in practical programming the data types that are common to procedural high-level languages: integer, real, char, string, Boolean, date (pseudocode will use the following data types: INTEGER, REAL, CHAR, STRING, BOOLEAN, DATE, ARRAY, FILE)
• show understanding of how character and string data are represented by software including the ASCII and Unicode character sets

ASCII = American Standard Code for Information Interchange

Drawback of ASCII

w16 11 Q8 [2]

• Only 256 characters can be represented
• Use one byte
• Many characters in other languages can’t be represented

Why Unicode is better than ASCII

w16 11 Q8 [2]

• Use 2 to 4 bytes
• Unicode is a superset of ASCII
• Most characters can be represented