String handling operations in a programming language: length

The idea

The length operation returns the number of characters in a string, including spaces and punctuation. In AQA 8525 pseudocode and most languages you apply it to a string variable, for example word ← "computer" then length(word) gives 8. Teach learners to count every character, not just letters: "hello world" has 11 characters because the space counts. Note that length returns an integer, so it can be compared, stored or used in a loop. Distinguish it from indexing, which returns a single character at a position. A common exam task asks for the output of a length expression or the value stored after assignment. Learners should trace the string character by character and state the integer result.

What earns the marks

• States that length returns the number of characters in the string as an integer.
• Counts spaces and punctuation as characters, e.g. "hello world" has 11 characters.
• Applies length to a named string variable and gives the correct integer for the given value.
• Distinguishes length (whole-string count) from position/indexing (single character).

Common mistakes and how to put them right

• Counting only letters and ignoring spaces.

  Put it right: Is to count every character including spaces and punctuation.

• Confusing length with the position of the last character.

  Put it right: Is that length is a count, so a string of 8 characters has length 8.

• Treating length as returning a character.

  Put it right: Is that it returns an integer count.

Exam tips

• Trace the string one character at a time, numbering each character to avoid miscounting.
• Write the integer answer clearly and check whether spaces are present before finalising.
• If asked for output, give the value only, not the expression.