Basic Stack Operations in C

Basic stack operations in C

"A stack is a basic computer science data structure and can be defined in an abstract, implementation-free manner, or it can be generally defined as a linear list of items in which all additions and deletion are restricted to one end that is Top." - Wikipedia

	/**
	* A Stack is a last in, first out (LIFO) abstract data type and data
	* structure.It is characterized by three fundamental operations: push,
	* pop and stack top.
	* PUSH : The push operation adds a new item to the top of the stack, or
	* initializes the stack if it is empty, but if the stack is full and
	* does not contain more space to accept the given item it is considered
	* as an Overflow state (It means that the stack is overloaded or no more
	* space for new item).
	* POP : The pop operation removes an item from the top of the stack,
	* but if the stack is empty then it goes into underflow state (It means
	* no items are present in the stack to be removed).
	* STACK TOP : The stack top operation gets the data from the top-most
	* position and returns it to the user without deleting it. The same
	* underflow state can also occur in stack top operation if stack is empty.
	**/
	#include<stdio.h>
	#define MAX 50
	int main()
	{
	int stack[MAX], top = -1, e;
	int choice;
	void PUSH(int *, int, int *);
	void POP(int *, int *);
	void DISPLAY_TOP(int *, int *);
	while(1) {
	printf("\nMenu\n1.PUSH\n2.POP\n3.DISPLAY STACK TOP\n4.EXIT\n");
	printf("Type 1 to Push, 2 to Pop, 3 to display and 4 to Exit : \n");
	scanf("%d", &choice);
	switch(choice) {
	case 1:
	printf("Enter element to be pushed : \n");
	scanf("%d", &e);
	PUSH(stack, e, &top);
	break;
	case 2:
	POP(stack, &top);
	break;
	case 3:
	DISPLAY_TOP(stack, &top);
	break;
	case 4:
	exit(0);
	default:
	printf("Invalid entry!!\n");
	}
	}
	return 0;
	}
	void PUSH(int *stack, int item, int *top)
	{
	if((*top) == MAX - 1) {
	printf("Stack Overflow!\n");
	return;
	} else {
	stack[++(*top)] = item;
	printf("%d inserted\n", item);
	}
	}
	void POP(int *stack, int *top)
	{
	int item;
	if((*top) == -1) {
	printf("Stack underflow\n");
	} else {
	item = stack[(*top)];
	printf("Popped item : %d\n", item);
	(*top)--;
	}
	}
	void DISPLAY_TOP(int *stack, int *top)
	{
	int i;
	if(*top == -1)
	printf("Stack underflow\n");
	else {
	printf("The stack contents are :\n");
	for(i = 0; i <= (*top); i++)
	printf("%d ",stack[i]);
	printf("\nThe top of the stack : %d\n", stack[(*top)]);
	printf("\n");
	}
	}

view raw stack.c hosted with ❤ by GitHub

Written by Munia Balayil