c - Queue sorting function sorts to the wrong queue -

here queue sorting function, dispatchlist, realtime, , jobqueue defined queue struct

struct queue {   pcbptr front;   pcbptr back; }; typedef struct queue queue; 

and pcbptr defined as

struct pcb { int pid;                         int arrival_time;    int time_left; int priority; int status;                      int printers; int modems; int scanners; int cds; int memory;         //might need struct memory block? struct pcb* next; struct pcb* prev; }; typedef struct pcb pcb; typedef pcb * pcbptr; 

now actual function

void starthostd(){   int i=0;   while(dispatchlist.front != null){     if(dispatchlist.front->priority == 0){         enqueue(dispatchlist.front, &realtime);         dispatchlist.front = dispatchlist.front->next;         printf("the %d pcb moved realtime queue\n", );     }     else{         enqueue(dispatchlist.front, &jobqueue);         dispatchlist.front = dispatchlist.front->next;         printf("the %d pcb moved job queue\n", );     }     i++;   }   while(realtime.front != null){     printf("blah");     realtime.front = realtime.front->next;   } } 

and here implementation of enqueue

void enqueue( pcbptr mypcb, queue* queue) {   if (queue->front == null){ //empty         queue->front = mypcb;   }   else{     queue->back->next = mypcb;    }   queue->back = mypcb; //set pcb end of queue } 

basically have 7 pcbptr in dispatchlist, first 4 have priority 1, 5th has priority 0, , last 2 have priority 1.

so should happen pcbs 1,2,3,4,6,7 should moved jobqueue, , pcb 5 should moved realtime.

when run program, proper print lines printed, output, expected:

the 0 pcb moved job queue 1 pcb moved job queue 2 pcb moved job queue 3 pcb moved job queue 4 pcb moved realtime queue 5 pcb moved job queue  6 pcb moved job queue 

(i know numbers in statement above behind 1)

but however, expected result should blah printed once, since there 1 pcb in realtime queue. however, printed 3 times, pcbs 5,6,7.

to me seems once 1 pcb moved realtime queue, every other element moved realtime queue well, though not supposed to.

can spot might missing?

thanks

ps: have side question, inserted usleep(5000) while loop prints "blah", not seem delay prints @ all, might cause of that?

the problem in how move elements 1 queue another. insert mypcb in queue, don't take account other elements linked it. have original list

job:      1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 realtime:  

then want move fifth element between queues, don't change links between nodes, , you've got this

job:      1 -> 2 -> 3 -> 4 -> 6 -> 7 realtime: 5 -> 6 -> 7 

to solve need change links in queue, guess work

if(dispatchlist.front->priority == 0){     pcbptr t = dispatchlist.front;     dispatchlist.front = dispatchlist.front->next;     t->next = null;     enqueue(t, &realtime);     printf("the %d pcb moved realtime queue\n", ); }