DS – Stack Program using Pointers – Ameerpet Technologies

#include<stdio.h>
int min, curr;
int *stack, *top;
void createStack();
void push();
void pop();
void traverse();
int main()
{
            int ch;
            createStack();
            printf(“Stack operations :\n”);
            while(1)
            {
                        printf(“1.Push \n”);
                        printf(“2.Pop \n”);
                        printf(“3.Display \n”);
                        printf(“4.Quit \n”);
                        printf(“Enter choice : “);
                        scanf(“%d”, &ch);
                        switch(ch)
                        {
                                    case 1 :            push();
                                                          break;
                                    case 2 :           pop();
                                                          break;
                                    case 3 :           traverse();
                                                          break;
                                    case 4 :           exit(1);
                                    default :           printf(“Invalid choice\n\n”);
                        }
            }
}
void createStack()
{
            printf(“Enter initial size : “);
            scanf(“%d”, &min);
            curr = min;
            stack = (int*)calloc(min, sizeof(int));
            if(stack==NULL)
            {
                        printf(“Stack creation failed\n”);
                        exit(0);
            }
            else
                        top = stack;
}
void push()
{
            int ele;
            printf(“Enter element to be pushed : “);
            scanf(“%d” , &ele);
            if(top==stack+curr)
            {
                        ++curr;
                        stack=(int*)realloc(stack, curr*sizeof(int));
                        if(stack==NULL)
                                    printf(“Unable to increase the size \n”);
                        else
                        {
                                    *top = ele;
                                    ++top;
                                    printf(“Element pushed…\n”);
                        }
            }
            else
            {
                        *top = ele;
                        ++top;
                        printf(“Element pushed…\n”);
            }
}
void pop()
{
            if(stack==top)
            {
                        printf(“Stack is Empty\n”);
            }
            –top;
            printf(“Popped : %d \n”, *top);
            if(curr>min)
            {
                        –curr;
                        stack = (int*)realloc(stack , curr*sizeof(int));
            }
}
void traverse()
{
            if(stack==top)
                        printf(“Stack is Empty\n”);
            else
            {
                        int* i;
                        printf(“Stack elements are : \n”);
                        for(i=top-1 ; i>=stack ; i–)
                        {
                                    printf(“%d \n”, *i);
                        }
            }
}

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