结构中带有指针变量的链表

Question

I am experiencing problems on linked list with pointer variables inside the struct. Everytime when i insert a new visitor data, the previous visitors data will all be changed to the most current visitor data.

    struct visitData{
    char *SrNo;
    char *ticketNo;
    char *Name;
    char *ID;
    };

   typedef struct ticket {
   struct visitData visitor;
   struct ticket *nextPtr;
   }tick;

   tick *addinfo(tick *previous,char* serial,char* ticketno,char* name,char* id)
   {

    tick *info = malloc(sizeof(tick));
    info->nextPtr = NULL;
    info->visitor.SrNo =serial;
    info->visitor.ticketNo = ticketno;
    info->visitor.Name = name;
    info->visitor.ID=id;

    if (previous != NULL)
    {
    previous->nextPtr = info;
    }


printf("visitor info has been added: %s %s %s %s",info->visitor.SrNo,info->visitor.ticketNo,info->visitor.Name,info->visitor.ID);

return info;

}

Answer 1

This should work:

#include <string.h>

tick *addinfo(tick *previous,char* serial,char* ticketno,char* name,char* id)
{

  tick *info = malloc(sizeof(tick));
  info->nextPtr = NULL;
  info->visitor.SrNo = strdup(serial);
  info->visitor.ticketNo = strdup(ticketno);
  info->visitor.Name = strdup(name);
  info->visitor.ID=strdup(id);

  if (previous != NULL)
  {
    previous->nextPtr = info;
  }


  printf("visitor info has been added: %s %s %s %s \n",info->visitor.SrNo,info->visitor.ticketNo,info->visitor.Name,info->visitor.ID);

  return info;
}

The problem was that you weren't allocating memory for your data. Also, be sure to free it when the program ends.