Array Index

What is Array Index?

The number in square brackets that selects one element of an array; it may be a literal or a variable, must lie between the declared lower and upper bounds, and may start at zero or one depending on the declaration.

This definition is part of the Programming chapter in Cambridge O Level Computer Science.

Concepts related to Array Index

• Array
• Iteration
• Variable
• out-of-range error

Common mistakes with Array Index

• M23. “Array indexes always start at 1.” TruthThe syllabus states that the first index can be zero or one. It is good practice to state the lower bound explicitly, because it defaults differently in different systems; generally a lower bound of 1 is used. DoRead the bound off the declaration and copy it into the loop, rather than assuming.