PUSH and POP algorithms in Linked List implemented STACK in C Language

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To implement the STACK using Linked List, the following PUSH and POP algorithms may be used:

Algorithm for PUSH operation in Linked List implemented STACK:

PUSHLL(TOP, ITEM)
[TOP is address of top node of STACK and ITEM is the item to PUSH.[In case of Linked List no overflow, but may be memory allocation error]
If AVAIL=NULL then:
  Write: ’Memory Allocation Error !!!’; Exit.
[End of If]
NEW<--AVAIL
AVAIL<--AVAIL-->LINK
NEW-->INFO<--ITEM
NEW-->LINK<--NULL
If TOP=NULL Then:
  TOP<--NEW
Else:
  NEW-->LINK<--TOP
   TOP<--NEW
[End of If]
Exit.

For Linked List implemented STACK in C, a self-referential structure, a user defined data type STACK is used, it is as follows:
struct STACK
  {
    int i:
    STACK *link:
   };

Algorithm for POP operation in Linked List implemented STACK.
POPLL(TOP)
[TOP is the address of TOP node of STACK]
If TOP=NULL Then:
   Write: ‘Underflow’
   Exit.
[End of If]
ITEM <--TOP-->INFO
TOP<--TOP-->LINK
Return ITEM
Exit.

Unknown
- January 29, 2015

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