Use meaningful identifier names and know why it is important to use them.

The idea

A meaningful identifier is a name a programmer chooses for something in a program so that its purpose is clear from reading it. Instead of naming a variable x or a, a programmer writes totalScore, itemPrice or pupilAge. The same applies to constants such as VAT_RATE and to subroutines such as calculateAverage. Meaningful names matter because programs are read far more often than they are written: by the original author returning later, by teammates, and by anyone debugging or maintaining the code. A clear name reduces the chance of mixing up two similar values, makes errors easier to spot, and removes the need for explanatory comments about what a value holds. In an exam question you may be asked to pick the better of two names, or to explain why one name is preferable.

What earns the marks

• A meaningful identifier clearly indicates the purpose or content of the item it names, for example totalScore for a running total.
• Meaningful names improve readability, so code is easier to understand when revisited or read by another programmer.
• Clear names reduce the risk of errors, such as confusing two similarly named variables or misusing a constant.
• Meaningful names make maintenance and debugging easier because the programmer can locate the relevant value quickly.
• Names must still obey identifier rules, such as starting with a letter and containing no spaces, while remaining descriptive.

Common mistakes and how to put them right

• Assuming any short name is acceptable because the program runs.

  Put it right: Is that a name must communicate purpose to a human reader, not merely satisfy the compiler or interpreter.

• Thinking a meaningful name must be very long.

  Put it right: Is that a concise but descriptive name such as itemPrice is better than an overlong phrase.

• Believing comments can fully replace good names.

  Put it right: Is that clear identifiers reduce the need for comments and keep the code itself self-explanatory.

Exam tips

• When comparing two names, state what each one tells the reader and choose the one whose purpose is clearer.
• Link the benefit to a concrete consequence, such as easier debugging or lower risk of mixing up values.
• Check the chosen name against identifier rules as well as readability, since a descriptive name with a space would still be invalid.