Implementation of circular queue in C/C++ ~ t3pedia

#include<stdio.h>

#include<conio.h>

#include<stdlib.h>

#include<iostream.h>

struct node

int info;

struct node* link;

};

struct node *last=0;

void main()

struct node*first=0;

int n;

clrscr();

struct node* add_first(struct node*);

struct node* add_last(struct node*);

struct node* del_first(struct node*);

struct node* del_last(struct node*);

void traverse(struct node*);

cout<<" \n 1.add at first ";

cout<<" \n 2.add at last ";

cout<<" \n 3.delete at first ";

cout<<" \n 4.delete at last ";

cout<<" \n 5.traverse ";

do

cout<<"\n enter your choice ";

cin>>n;

     switch(n)

         case 1:first=add_first(first);

         break;

         case 2:first=add_last(first);

         break;

         case 3:first=del_first(first);

         break;

         case 4:first=del_last(first);

         break;

         case 5:traverse(first);

     break;

         default: cout<<"\n\n invalid entry ";

         exit(0);

}     while(n!=0);

getch();

struct node *add_first(struct node *f)

struct node* nw;

nw=(struct node*)malloc(sizeof(struct node));

cout<<"\n enter the value of node ";

cin>>nw->info;

    if(f==0)

        last=nw;

        nw->link=nw;

        return(nw);

 else

     nw->link=f;

     f=nw;

     last->link=nw;

     return(f);

struct node* add_last(struct node *f)

struct node* nw;

nw=(struct node*)malloc(sizeof(struct node));

cout<<"\n enter the value of node ";

cin>>nw->info;

    if(f==0)

     nw->link=nw;

     last=nw;

     return(nw);

     else

     last->link=nw;

     nw->link=f;

     last=nw;

     return(f);

struct node* del_first(struct node *f)

    if(f==0)

    cout<<"\n list is empty";

    return(f);

    else

    f=f->link;

    last->link=f;

    cout<<"\n node is deleted ";

    return(f);

struct node* del_last(struct node* f)

    if(f==0)

    cout<<" \n link list is empty ";

    return(f);

    else

     struct node* save=f;

        while(save->link!=last)

            save=save->link;

            save->link=f;

            last=save;

            cout<<"\n node is deleted ";

            return(f);

void traverse(struct node* f)

if(f==0)

cout<<"link list is empty ";

else

struct node* save;

cout<<"\n\n";

while(save->link!=f)

cout<<save->info<<"  ";

save=save->link;

cout<<save->info<<"\n\n";

Pages