Search results
Results From The WOW.Com Content Network
A stack can be easily implemented either through an array or a linked list, as it is merely a special case of a list. [19] In either case, what identifies the data structure as a stack is not the implementation but the interface: the user is only allowed to pop or push items onto the array or linked list, with few other helper operations.
In such case it is always possible to use a function call, but this can be cumbersome and inelegant. For example, to pass conditionally different values as an argument for a constructor of a field or a base class, it is impossible to use a plain if-else statement; in this case we can use a conditional assignment expression, or a function call ...
Stack-based algorithms manipulate data by popping data from and pushing data to the stack. Operators govern how the stack manipulates data. To emphasize the effect of a statement, a comment is often used showing the top of the stack before and after the statement; this is known as the stack effect diagram.
The problem in this case exists if the compose function allocates the parameter variables f and g on the stack. When compose returns, the stack frame containing f and g is discarded. When the internal function λx attempts to access g, it will access a discarded memory area.
Within an imperative programming language, a control flow statement is a statement that results in a choice being made as to which of two or more paths to follow. For non-strict functional languages, functions and language constructs exist to achieve the same result, but they are usually not termed control flow statements.
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 .
Duff's device provides a compact loop unrolling by using the case keyword both inside and outside the loop. This is unusual because the contents of a case statement are traditionally thought of as a block of code nested inside the case statement, and a reader would typically expect it to end before the next case statement.
More exactly, if the item is an identifier, the value pushed onto the stack will be the binding for that identifier in the current environment E. If the item is an abstraction, a closure is constructed to preserve the bindings of its free variables (which are in E ), and it is this closure which is pushed onto the stack.