Data types: character

The idea

A character is a single symbol stored by a computer, such as a letter, digit, punctuation mark or space. In AQA 8525 you must recognise that a character data type holds exactly one symbol, not a whole word or sentence. Each character is stored using a character code, for example ASCII or Unicode, so the letter A is held as a numeric code rather than as a picture of the letter. A useful test is to ask how many symbols are being stored: 'A' is one character, while 'Apple' is five characters and would be a string. When answering, distinguish the character itself from its code, and remember that a space or a digit such as 7 can also be a character.

What earns the marks

• A character is a single symbol, such as a letter, digit, punctuation mark or space.
• A character is stored using a character code such as ASCII or Unicode.
• A character holds exactly one symbol, whereas a string holds a sequence of characters.
• Digits and spaces can be characters, not only letters.
• The character value is distinct from the numeric code used to store it.

Common mistakes and how to put them right

• Thinking a character can hold a whole word.

  Put it right by stating that a word of several symbols is a string, and a character is exactly one symbol.

• Confusing the character with its code.

  Put it right by separating the symbol stored from the numeric code (such as ASCII or Unicode) used to represent it.

• Assuming only letters count as characters.

  Put it right by including digits, punctuation and spaces as single characters.

Exam tips

• Count the symbols in the value to decide whether it is a character or a string.
• Link the character to a character set such as ASCII or Unicode when explaining storage.
• Check whether the question asks for the symbol itself or the code that represents it.