• Michael Comperchio <mcmprch adelphia.net> Sep 23 2002
• Jan Knepper <jan smartsoft.cc> Sep 23 2002
• Michael Comperchio <mcmprch adelphia.net> Sep 23 2002
• Al Bowers <abowers combase.com> Sep 26 2002

Michael Comperchio <mcmprch adelphia.net> writes:

I'm confused by declarations. I'm trying to dynamically create an array 
of pointers to classes. so:


#include 
<stdio.h>
#include <string.h>

class emails
{
public:
     emails(){};
     emails(char *FName, char *LName, char *EMail, int ID){
	    strcpy(fname, FName);
	    strcpy(lname, LName);
	    strcpy(email , EMail);
	    id = ID;
     };

	char * GetName() const { return strcat(fname,lname);};
	void SetName(char * Fname, char *Lname){
	    strcpy(fname, Fname);
	    strcpy(lname, Lname);
	}
	char * GetEmail() const { return email;};
	void SetEmail( char * EMail) { strcpy(email,EMail);};

private:

	char fname[50];
	char lname[50];
     char email[50];
	int id;
};


void main(int argc, char *argv[])

{
    {
     /* Print a prompt prior to exiting so that you can view output */
     emails *local_emails[];
// I read this as: local_mails is an array of pointers to 
emails...however... the compiler tells me size of array is not 
known...ok so
     emails **local_emails;

//it doesn't like this either...can I do something like this in C++????

     local_emails = new emails[10];

     printf("Press a character....\n");
     getch();
    }
}

Jan Knepper <jan smartsoft.cc> writes:

Michael Comperchio wrote:

     {
      /* Print a prompt prior to exiting so that you can view output */
      emails *local_emails[];
 // I read this as: local_mails is an array of pointers to
 emails...however... the compiler tells me size of array is not
 known...ok so
      emails **local_emails;


Ok, than:
    const int         LOCAL_EMAILS  = 10;
    local_emails    = new  ( emails * ) [ LOCAL_EMAILS ];

    for ( int  i = 0 ; i < LOCAL_EMAILS ; i++ )
        *( local_emails + i ) = new  emails ();

 //it doesn't like this either...can I do something like this in C++????


    emails       *local_emails;        // This should do for new  emails [
10 ];

      local_emails = new emails[10];

      printf("Press a character....\n");
      getch();
     }
 }

Michael Comperchio <mcmprch adelphia.net> writes:

Jan Knepper wrote:
 Michael Comperchio wrote:
 
 
    {
     /* Print a prompt prior to exiting so that you can view output */
     emails *local_emails[];
// I read this as: local_mails is an array of pointers to
emails...however... the compiler tells me size of array is not
known...ok so
     emails **local_emails;


 
 Ok, than:
     const int         LOCAL_EMAILS  = 10;
     local_emails    = new  ( emails * ) [ LOCAL_EMAILS ];
 
     for ( int  i = 0 ; i < LOCAL_EMAILS ; i++ )
         *( local_emails + i ) = new  emails ();
 
 
//it doesn't like this either...can I do something like this in C++????


 
     emails       *local_emails;        // This should do for new  emails [
 10 ];
 
 
     local_emails = new emails[10];

     printf("Press a character....\n");
     getch();
    }
}


 


the actual number of emails is not known until runtime (the number of 
rows returned from a DB call)...but that's seems to be ok as this works...

emails **local_email;
....

local_email = new (emails * [res.size() * sizeof(emails *)]);
the key was (emails *...) I was stuck in my stubborn way on using ...new 
emails[res.size() * sizeof(emails *)]

Al Bowers <abowers combase.com> writes:

Michael Comperchio wrote:

 I'm confused by declarations. I'm trying to dynamically create an array 
 of pointers to classes. so:


..............code snipped..............

Since you are using C code, you could use function malloc.

You need to watch the char arrays. The way you are copying to them is 
very dangerous.

Ex.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

class emails
{
public:
     emails(){};
     emails(char *FName, char *LName, char *EMail, int ID){
         strcpy(fname, FName);
         strcpy(lname, LName);
         strcpy(email , EMail);
         id = ID;
     };

     char * GetName()  { return strcat(fname,lname);};
     void SetName(char * Fname, char *Lname){
         strncpy(fname, Fname,48);
         fname[48]='\0';
         strcat(fname," ");
         strncpy(lname, Lname,49);
         lname[49]='\0';
     }
     char * GetEmail()  { return email;};
     void SetEmail( char * EMail) {
		 strncpy(email,EMail,49);
	     email[49]='\0';
	};

private:

     char fname[100];
     char lname[50];
     char email[50];
     int id;
};


void main(int argc, char *argv[])   {
    emails *local_emails;

    if((local_emails=(emails *)malloc(10*sizeof(emails)))==NULL)
       exit(EXIT_FAILURE);

    int i;
    for(i = 0;i <10;i++)
       local_emails[i].SetName("George","Washington");
    for(i = 0;i <10;i++)
       printf("local_emails[%i] name: %s\n",
               i,local_emails[i].GetName());
    free(local_emails);
    printf("\nDa size of emails * = %u\n"
           "Da size of emails = %u\n\n",sizeof(emails *),
                        sizeof(emails));
    printf("Da End....\n");
    }