Question

here is queue implementation which gives me very unclear error

#include<iostream>
#include "bool.h"
#include "item.h"
#include "queue.h"

using namespace std;

void init_queue(queue *q){
    q->first=0;
    q->last=queuesize-1;
    q->count=0;

}
       void enqueue (queue *q,item_type x){
           if(q->count>=queuesize)
               cout<<" queue everflow occurs during enqueue "<<endl;
           else
           {
               q->last=(q->last+1)%queuesize;
               q->m[q->last]=x;
               q->count=q->count+1;

           }




       }

             int dequeue (queue *q)
             {
                 item_type x;
                 if(q->count<=0) cout<<"empthy queue "<<endl;
                 else
                 {
                     x=q->m[q->first];
                     q->first=(q->first+1)%queuesize;
                     q->count=q->count-1;
                 }
                 return (x);




                 }



             item_type headq(queue *q)
             {
                 return(q->m[q->first]);
             }
             int empthy(queue *q){


                 if (q->count<=0) return (TRUE);
                 else return (FALSE);
             }

 void print_queue(queue *q){
     int i;
     i=q->first;
     while(i!=q->last)
     {
         cout<<q->m[i];
         i=(i+1)%queuesize;
     }
     cout<<q->m[i]<<"  ";

 }
 int main(){
     queue *q;
     init_queue(q);
 int a;
 while(cin>>a){
     enqueue(q,a);




 }
 print_queue(q);


    return 0;
}

see also please queue header file

#define  queuesize 1000
#include "item.h"

typedef struct
{
int  m[queuesize+1];
  int first;
  int last;
  int count;
  }queue;

error is that (actualy) it is not error just warning when i compile,but when i run it says local variable q uninitialized,so which variable q?it is name of structure,so when i run init_queue method it should initialize yes?

Answer 1

 queue *q;      
init_queue(q); 

You are not allocating the memory for q.

queue *q = new queue;

You can allocate the queue on stack as well: ( recommended !)

queue q;
   init_queue(&q);