Converting from C to C++

This is a discussion on Converting from C to C++ within the C++ Programming forums, part of the General Programming Boards category; Hey guys. I have the below code in C but I need to convert it to C++, any ideas about ...

  1. #1
    Registered User
    Join Date
    Aug 2006
    Posts
    127

    Converting from C to C++

    Hey guys. I have the below code in C but I need to convert it to C++, any ideas about where to start and what would need to change majorly would be appreciated.

    Code:
    #include<stdio.h>
    #include<stdlib.h>
    #include<string.h>
    #include<unistd.h>
    
    #define DELIM ":"
    
    struct pktnode
    {
       int pkt_id;
       char *message;
       struct pktnode *next;
    };
    
    struct messagenode
    {
       int msg_id;
       int prefix_len;
       char id_prefix[3];
       struct pktnode *pkthead;
       struct messagenode *next;
    };
    
    void initiate(char *filename, FILE **fp, char **packet);
    void populateInList(char *packet, struct messagenode **msg_node, FILE **fp);
    struct messagenode *getMsgNode();
    struct pktnode *getPktNode();
    struct messagenode *search_msg(int msg_id, struct messagenode **head_msg);
    struct pktnode *search_pkt(int pkt_id, struct pktnode **head_pkt);
    void getPacketInfo(char *packet, int *msg_id, int *pkt_id, char *message, 
       int *prefix_len_msg, struct messagenode **head_msg, FILE **fp);
    void display(struct messagenode **head_msg);
    void cleanUpAll(struct messagenode **head_msg, FILE **fp, char *packet);
    void sortMsg(struct messagenode **head_msg);
    int getlen(char *arg);
    
    int main(int argc, char **argv)
    {
       FILE *fp;
       char *packet;
       struct messagenode *head_msg = NULL;
       
       if(argc != 2)
       {
          printf("Must supply 1 argument to packet\n");
          return 0;
       }
       initiate(argv[1], &fp, &packet);
    
       while(1)
       {
          fgets(packet, 2001, fp);
    
          if(packet == NULL || !strcmp(packet, "END\n")|| !strcmp(packet, "END"))
             break;
          populateInList(packet, &head_msg, &fp);
       }
       sortMsg(&head_msg);
    
       display(&head_msg);
       
       cleanUpAll(&head_msg, &fp, packet);
       return 0;
    }
    
    /* Opening packet data file */
    
    void initiate(char *filename, FILE **fp, char **packet)
    {
       *fp = fopen(filename, "r");
       if(*fp == NULL)
       {
          printf("Unable to open %s\n", filename);
          exit(0);
       }
       *packet = (char *)malloc(2000 * sizeof(char));
    }
    
    /* Get message id, packet id and packet message from each
     * packet string passed to function as argument.
     */   
    
    void populateInList(char *packet, struct messagenode **head_msg, FILE **fp)
    {
       int msg_id, pkt_id, prefix_len_msg;
       char *message;
       struct messagenode *tmp_message, *loc, *current_msg, *save_msg;
       struct pktnode *tmp_packet, *loc_pkt, *head_pkt;
    
       message = (char *)malloc(1500*sizeof(char));
       
       getPacketInfo(packet, &msg_id, &pkt_id, message, 
          &prefix_len_msg, head_msg, fp);
       
       if((loc = search_msg(msg_id, head_msg)) != NULL)
       {
          tmp_packet = getPktNode();
          tmp_packet->pkt_id = pkt_id;
          tmp_packet->message = message;
    
          head_pkt = loc->pkthead;
    
          if(head_pkt == NULL)
             head_pkt = tmp_packet;
          else 
          {
             loc_pkt = search_pkt(pkt_id, &head_pkt);
    
             if(loc_pkt == head_pkt && pkt_id < loc_pkt->pkt_id)
             {
                tmp_packet->next = head_pkt;
                head_pkt = tmp_packet;
                loc->pkthead = head_pkt;
             }
             else
             {
                tmp_packet->next = loc_pkt->next;
                loc_pkt->next = tmp_packet;
             }
          }
       }
       else
       {
          tmp_message = getMsgNode();
          tmp_message->msg_id = msg_id;
          tmp_message->prefix_len = prefix_len_msg;
          tmp_message->next = NULL;
          tmp_message->pkthead = getPktNode();
          tmp_message->pkthead->pkt_id = pkt_id;
          tmp_message->pkthead->message = message;
          if(*head_msg == NULL)
             *head_msg = tmp_message;
          else 
          {
             current_msg = *head_msg;
             while(current_msg != NULL)
             {
                save_msg = current_msg;
                current_msg = current_msg->next;
             }
             save_msg->next = tmp_message;
          }
       }
    }
    
    struct messagenode *getMsgNode()
    {
       struct messagenode *tmp;
    
       tmp = (struct messagenode *)malloc(sizeof(struct messagenode));
       tmp->pkthead = NULL;
       return tmp;
    }
    
    struct pktnode * getPktNode()
    {
       struct pktnode *tmp;
    
       tmp = (struct pktnode *)malloc(sizeof(struct pktnode));
       tmp->next = NULL;
       return tmp;
    }
    
    /* Function to search a message node in message linked list. */
    
    struct messagenode *search_msg(int msg_id, struct messagenode **head_msg)
    {
       struct messagenode *current_msg;
    
       current_msg = *head_msg;
       if(*head_msg == NULL)
          return NULL;
       else 
       {
          while((current_msg != NULL) && (current_msg->msg_id != msg_id))
             current_msg = current_msg->next;
          if(current_msg == NULL)
             return NULL;
          if(current_msg->msg_id == msg_id)
             return current_msg;
          else
             return NULL;
       }
    }
    
    /* Function to search a packet node in packet linked list. */
    
    struct pktnode *search_pkt(int pkt_id, struct pktnode **head_pkt)
    {
       struct pktnode *current_pkt, *save_pkt;
       
       current_pkt = *head_pkt;
       save_pkt = current_pkt;
       while((current_pkt != NULL) && (pkt_id > current_pkt->pkt_id))
       {
          save_pkt = current_pkt;
          current_pkt = current_pkt->next;
       }
       return save_pkt;
    }
    
    /* Function to get packet info from packet string. */
    
    void getPacketInfo(char *packet, int *msg_id, int *pkt_id, char *message, 
       int *prefix_len_msg, struct messagenode **head_msg, FILE **fp)
    {
       char *tokenPtr = NULL;
       char array[10][1500];
       char bkp_packet[2000];
       int counter = 0, i=0;
       
       strcpy(bkp_packet, packet);
    
       tokenPtr = (char *)strtok(packet, DELIM);
       if(tokenPtr == NULL)
       {
          printf("Fatal Error1 !! Invalid Message Format\n");
          cleanUpAll(head_msg, fp, packet);
          exit(0);
       }
       strcpy(array[0], tokenPtr);
       counter++;
    
       while(1)
       {
          tokenPtr = (char *)strtok(NULL, DELIM);
          if(tokenPtr == NULL)
             break;
          strcpy(array[counter], tokenPtr);
       
          if(counter>2)
             strcat(array[counter-1], ":");
          counter++;
       }
       if(counter < 3)
       {
          printf("Fatal Error3 !! Invalid Message Format\n");
          cleanUpAll(head_msg, fp, packet);
          exit(0);
       }
       *prefix_len_msg = getlen(array[0]);
       *msg_id = atoi(array[0]);
       *pkt_id = atoi(array[1]);
       for(i=2; i<counter; i++)
       {
          strcat(message, array[i]);
       }
    }
    
    int getlen(char *arg)
    {
       int n=0;
       char ch;
    
       while(1)
       {
          ch = arg[n];
          if(ch != '0')
             break;
          n++;
       }
       return n;
    }
    
    /* Move through formulated linked list and display the content.*/
    
    void display(struct messagenode **head_msg)
    {
       char display_string[2000];
       char prefix[3];
       struct messagenode *current_msg;
       struct pktnode *current_pkt;
       int i;
    
       current_msg = *head_msg;
       while(current_msg != NULL)
       {
          for(i=0; i<current_msg->prefix_len; i++)
             prefix[i]= '0';
          prefix[i]='\0';
          sprintf(display_string, "Message %s%d\n", prefix, current_msg->msg_id);
          current_pkt = current_msg->pkthead;
          while(current_pkt != NULL)
          {
             strcat(display_string, current_pkt->message);
             current_pkt = current_pkt->next;
          }
          current_msg = current_msg->next;
          printf("%s\n", display_string);
       }
    }
    
    /* Move through linked list and deallocate it. Close file pointer also */
    
    void cleanUpAll(struct messagenode **head_msg, FILE **fp, char *packet)
    {
       struct messagenode *current_msg, *head_msg_local;
       struct pktnode *current_pkt, *head_pkt;
    
       fclose(*fp);
       free(packet);
    
       head_msg_local = *head_msg;
       while(head_msg_local != NULL)
       {
          head_pkt = head_msg_local->pkthead;
          while(head_pkt != NULL)
          {
             free(head_pkt->message);
             current_pkt = head_pkt->next;
             free(head_pkt);
             head_pkt = current_pkt;
          }
          current_msg = head_msg_local->next;
          free(head_msg_local);
          head_msg_local = current_msg;
       }
    }
    
    /* Sort the message linked list, i.e. the outer one.*/
    
    void sortMsg(struct messagenode **head_msg)
    {
       int tmp_id, tmp_len;
       struct pktnode *tmp_head;
       struct messagenode *current_msg, *save_msg;
       
       if(*head_msg == NULL)
          return;
       else 
       {
          for(current_msg = *head_msg; (current_msg != NULL);
             current_msg = current_msg->next)
          {
             for(save_msg = current_msg->next; 
                (save_msg != NULL); save_msg = save_msg->next)
             {
                if(current_msg->msg_id > save_msg->msg_id)
                {
                   tmp_id = save_msg->msg_id;
                   tmp_head = save_msg->pkthead;
                   tmp_len = save_msg->prefix_len;
    
                   save_msg->msg_id = current_msg->msg_id;
                   save_msg->pkthead = current_msg->pkthead;
                   save_msg->prefix_len = current_msg->prefix_len;
    
                   current_msg->msg_id = tmp_id;
                   current_msg->pkthead = tmp_head;
                   current_msg->prefix_len = tmp_len;
                }
             }
          }
       }
    }

  2. #2
    and the hat of sweating
    Join Date
    Aug 2007
    Location
    Toronto, ON
    Posts
    3,545
    Rename the file from .c to .cpp and recompile.
    If there are any errors, post them and we'll take a look.
    For the most part, C++ is C plus some extra stuff.
    I'm a firm believer in the saying "If it ain't broke, don't fix it".
    "I am probably the laziest programmer on the planet, a fact with which anyone who has ever seen my code will agree." - esbo, 11/15/2008

    "the internet is a scary place to be thats why i dont use it much." - billet, 03/17/2010

  3. #3
    Unregistered User Yarin's Avatar
    Join Date
    Jul 2007
    Posts
    1,628
    You could change the mallocs and frees to news and deletes?
    A class that doesn't overload all operators just isn't finished yet. -- SmugCeePlusPlusWeenie
    A year spent in artificial intelligence is enough to make one believe in God. -- Alan J. Perlis

  4. #4
    Registered User
    Join Date
    Apr 2008
    Posts
    890
    I tend to side with cp here - why do you "need" to convert it? If it's working, at most I might put it behind a facade or wrap it.

    If you just want to learn, on the other hand, a first step would be to turn the structs into classes, and make functions that operate on them into member functions of those classes.

    So, instead of...

    Code:
    struct foo {};
    
    void doSomething(foo *) {}
    Do this...

    Code:
    class foo {
    public:
        void doSomething() {}
    };

  5. #5
    Unregistered User Yarin's Avatar
    Join Date
    Jul 2007
    Posts
    1,628
    Why do this?
    Most compilers allow you to compile C and C++ files in the same project (program), at the same time.
    A class that doesn't overload all operators just isn't finished yet. -- SmugCeePlusPlusWeenie
    A year spent in artificial intelligence is enough to make one believe in God. -- Alan J. Perlis

  6. #6
    Kernel hacker
    Join Date
    Jul 2007
    Location
    Farncombe, Surrey, England
    Posts
    15,677
    As discussed, it depends on how far you want to take it. The difficulty ranges from "renaming the file" (and fixing any compiler errors that crop up) to "making the application entirely object oriented".

    One thing that comes to mind is to use the STL containers (e.g. list) instead of using your home-made linked list system.

    I don't think there is much point in ONLY replacing malloc with new and free with delete - malloc and free are still valid C++ code as long as there is no need to construct an object from the pointer.

    In an ultimate made object oriented, you'd have a packet object and a messagenode object which you can manipulate through member functions. That would be essentially a complete rewrite of the code.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. Converting 32 bit binary IP to decimal IP (vice-versa)
    By Mankthetank19 in forum C Programming
    Replies: 15
    Last Post: 12-28-2009, 06:17 PM
  2. Tips for converting C prog. to C++?
    By eccles in forum C++ Programming
    Replies: 7
    Last Post: 01-15-2005, 06:38 AM
  3. Converting Sign Magnitude Integer Binary Files
    By Arthur Dent in forum C Programming
    Replies: 7
    Last Post: 09-13-2004, 10:07 AM
  4. Converting from Screen to World Coordinates
    By DavidP in forum Game Programming
    Replies: 9
    Last Post: 05-11-2004, 12:51 PM
  5. converting string to float
    By twhubs in forum C Programming
    Replies: 1
    Last Post: 09-16-2001, 09:02 AM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21