Question

When I try to delete the structure that I got from Queue.It will throw runtime heap error.

here is my sample.

   /* "Message_content" structure hold the content of message and body. */
   typedef struct msgContent
   {
     char *message;
     char *body;
     struct msgContent *nextptr;
   }Message_content;

static Message_content *frontptr;
static Message_content *rearptr;

Message_content* msgContent;
msgContent = QueueDelete();
free(msgContent); //**error happens while calling this function**.

Here is my QueueDelete() function in c.

static Message_content* QueueDelete()
{
Message_content *tempMsgContent = NULL;

if(frontptr == NULL)
{
}
else if(frontptr==rearptr)
{
    tempMsgContent = frontptr;
    tempMsgContent->nextptr = NULL;
    frontptr = rearptr = NULL;
}
else
{
    tempMsgContent = frontptr;

    frontptr = frontptr->nextptr;
            tempMsgContent->nextptr = NULL; // rectify the problem said by philong
}
return tempMsgContent;
}

EDIT
Add Queue Insert Function which will give meaning to my code.

here is my Queue Insert function in c

  static int QueueInsert(char *message ,char *body)
  {
    Message_content *tempMsgContent  = (Message_content*) malloc(sizeof(Message_content*));
   if(rearptr == NULL && frontptr == NULL) 
   {
    rearptr = tempMsgContent;
    rearptr->message = message;
    rearptr->body = body;
    rearptr->nextptr=NULL;
    frontptr = rearptr;
    return 1;
   }
    rearptr->nextptr = tempMsgContent;
    rearptr = rearptr->nextptr;
    rearptr->body = body;
    rearptr->message = message;
    rearptr->nextptr = NULL;
    return 1;
    }

Answer 1

This might be your problem:

tempMsgContent = frontptr;
tempMsgContent->nextptr = NULL;
frontptr = frontptr->nextptr;

You set the nextptr of tempMsgContent to NULL, which is good, but frontptr and tempMsgContent still point to the same memory location!

Set the nextptr to NULL after changing the frontptr.

Edit Checking through your QueueInsert code, I see this line:

Message_content *tempMsgContent  = (Message_content*) malloc(sizeof(Message_content*));

What that does is allocate memory enough for a pointer (sizeof(Message_Content*))! You should use sizeof(Message_Content) without the asterisk. This will certainly mess upp your heap!