Data types: string.

The idea

A string is a sequence of characters treated as one item of data, such as a name, a postcode or a sentence. In AQA 8525 you must recognise that a string can hold zero, one or many characters, so 'A' can be a string of length one and 'Hello' is a string of length five. Strings are stored as a series of character codes, and operations such as finding the length or joining strings work on the whole sequence. A useful test is whether the value is made of several symbols in order: if so, it is a string rather than a single character. Remember that a string may include digits and spaces, for example a postcode.

What earns the marks

• A string is a sequence of characters treated as a single data item.
• A string can contain letters, digits, spaces and punctuation.
• A string may hold zero, one or many characters, so length can vary.
• Strings are stored as a series of character codes.
• A string differs from a character because it can hold more than one symbol.

Common mistakes and how to put them right

• Believing a string must contain more than one character.

  Put it right by noting a string can hold zero or one character as well as many.

• Thinking a string can only contain letters.

  Put it right by including digits, spaces and punctuation in a string.

• Treating a string as a single character code.

  Put it right by explaining a string is stored as a series of character codes.

Exam tips

• Count the symbols to confirm a value is a string and state its length.
• Give a realistic example such as a name or postcode to show a string in use.
• Contrast a string with a character to make the difference clear.