Wednesday, 21 September 2016

Stack Using Singly Linked List

Stack using Singly Linked List



#include<stdio.h>
#include<stdlib.h>
struct stack
{
            int data;
            struct stack  *link;
};

typedef struct stack * NODE;
NODE top = NULL;

void insert_front(int item);
NODE delete_front();
void display();

NODE getnode()
{
            NODE x;
            x = (NODE)malloc(sizeof(struct stack));
            x->link = NULL;
}

void insert_front(int item)
{
            NODE temp;
            temp = getnode();
            temp->data = item;

            if(top != NULL)
            {
                        temp->link = top;
            }
            top = temp;
}

NODE delete_front()
{
            NODE temp;
            if(top == NULL)
            {
                        printf("\nStack underflow");
                        return NULL;
            }
            else
            {
                        temp = top;
                        top = top->link;
                        printf("\nItem got deleted is: %d", temp->data);
                        free(temp);
                        return top;
            }
}

void display()
{
            NODE cur;
            if(top == NULL)
            {
                        printf("\nStack is empty");      
            }
            else
            {
                        printf("\nContents are: \n");
                        cur  = top;
                        while(cur!=NULL)
                        {
                                                printf("| %d |\n", cur->data);
                                                cur = cur->link;
                        }
            }
}

void main()
{
            int ch, item;
            while(1)
            {
                        printf("\n~~MENU~~");
                        printf("\n1.Push operation");
                        printf("\n2.Pop operation");
                        printf("\n3.Display");
                        printf("\nEnter your choice: ");
                        scanf("%d", &ch);
                        switch(ch)
                        {
                                                case 1:           printf("\nEnter the item to be inserted: ");
                                                                      scanf("%d", &item);
                                                                      insert_front(item);
                                                                      display();
                                                                      break;
                                                case 2:           top = delete_front();
                                                                      display();
                                                                      break;
                                                case 3:           display();
                                                                      break;
                                                case 4:           exit(0);
                        }
            }
}

Output:

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 1

Enter the item to be inserted: 11
Contents are:
| 11 |

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 1

Enter the item to be inserted: 12
Contents are:
| 12 |
| 11 |

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 1

Enter the item to be inserted: 13
Contents are:
| 13 |
| 12 |
| 11 |

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 1

Enter the item to be inserted: 14
Contents are:
| 14 |
| 13 |
| 12 |
| 11 |

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 2

Item got deleted is: 14
Contents are:
| 13 |
| 12 |
| 11 |

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 2

Item got deleted is: 13
Contents are:
| 12 |
| 11 |

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 2

Item got deleted is: 12
Contents are:
| 11 |

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 2

Item got deleted is: 11
Stack is empty

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 2

Stack underflow
Stack is empty

~~MENU~~
1.Push operation
2.Pop operation
3.Display
Enter your choice: 4

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