Some Important Linear Data Structures- at a glance
Stack is a specialized data storage structure (Abstract data type). Unlike, arrays access of elements in a stack is restricted. It has two main functions push and pop. Insertion in a stack is done using push function and removal from a stack is done using pop function. Stack allows access to only the last element inserted hence, an item can be inserted or removed from the stack from one end called the top of the stack. It is therefore, also called Last-In-First-Out (LIFO) list. Stack has three properties: capacity stands for the maximum number of elements stack can hold, size stands for the current size of the stack and elements is the array of elements.
Stack structure is defined with fields capacity, size and *elements (pointer to the array of elements).
1. createStack function– This function takes the maximum number of elements (maxElements) the stack can hold as an argument, creates a stack according to it and returns a pointer to the stack. It initializes Stack S using malloc function and its properties.
2. push function - This function takes the pointer to the top of the stack S and the item (element) to be inserted as arguments. Check for the emptiness of stack
3. pop function - This function takes the pointer to the top of the stack S as an argument.
4. top function – This function takes the pointer to the top of the stack S as an argument and returns the topmost element of the stack S.
1. Each function runs in O(1) time.
2. It has two basic implementations
Array-based implementation – It is simple and efficient but the maximum size of the stack is fixed.
Singly Linked List-based implementation – It’s complicated but there is no limit on the stack size, it is subjected to the available memory.
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