stapel

Stapel means a pile of objects arranged one on top of another. In everyday Dutch, it can refer to a heap or stack of items, such as a stack of books. The term is used in computing as the Dutch translation of the English "stack."

In computer science, a stack is a last-in, first-out data structure that stores a collection of elements with insertion and removal at the top. The main operations are push (toevoegen aan de stapel), pop (verwijderen van de stapel), and peek/top (toegang tot het bovenste element without removing). Additional helpers include isEmpty and size. A stack can be implemented using an array or a linked list.

Time complexity: push and pop are typically O(1). Memory is proportional to the number of elements. In many languages, there is a runtime call stack that records active function calls, with each frame representing a stack element, including return addresses and local variables.

Applications include evaluating expressions in postfix notation, backtracking algorithms, parsing, and undo mechanisms. In programming language runtimes, the call stack manages function calls and returns and can be a source of stack overflow if too deep.

Etymology: "stapel" comes from Dutch for a pile, from older Germanic roots; related terms exist in Dutch and Flemish. The concept of a stack is present in many computer science contexts.