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The name "peek" is similar to the basic "push" and "pop" operations on a stack, but the name for this operation varies depending on data type and language. Peek is generally considered an inessential operation, compared with the more basic operations of adding and removing data, and as such is not included in the basic definition of these data ...
An example of a non-essential operation is "top of stack", or "peek", which observes the top element without removing it from the stack. [18] Since this can be broken down into a "pop" followed by a "push" to return the same data to the stack, it is not considered an essential operation.
As most early home computers used 8-bit processors, PEEK or POKE values are between 0 and 255. Setting or reading a 16-bit value on such machines requires two commands, such as PEEK (A) + 256 * PEEK (A + 1) to read a 16-bit integer at address A, and POKE A, V followed by POKE A + 1, V / 256 to store a 16-bit integer V at address A.
procedure iterativePostorder(node) if node = null return stack ← empty stack lastNodeVisited ← null while not stack.isEmpty() or node ≠ null if node ≠ null stack.push(node) node ← node.left else peekNode ← stack.peek() // if right child exists and traversing node // from left child, then move right if peekNode.right ≠ null and ...
This type of stack is also known as an execution stack, program stack, control stack, run-time stack, or machine stack, and is often shortened to simply the "stack". Although maintenance of the call stack is important for the proper functioning of most software , the details are normally hidden and automatic in high-level programming languages .
With a stack stored completely in RAM, this does implicit writes and reads of the in-memory stack: Load X, push to memory; Load 1, push to memory; Pop 2 values from memory, add, and push result to memory; for a total of 5 data cache references. The next step up from this is a stack machine or interpreter with a single top-of-stack register.
Input: 3 + 4 Push 3 to the output queue (whenever a number is read it is pushed to the output); Push + (or its ID) onto the operator stack; Push 4 to the output queue; After reading the expression, pop the operators off the stack and add them to the output.
A queue has two ends, the top, which is the only position at which the push operation may occur, and the bottom, which is the only position at which the pop operation may occur. A queue may be implemented as circular buffers and linked lists, or by using both the stack pointer and the base pointer.