Pointer to struct

[subdene]

Can anyone help me on this. If you have got an array of structures pointed to by a pointer, how do you access the subscript and then the subsequent members of that structure?
Thanks

[Dual-Catfish]

struct house {
    int people;
    int toilets;
    char *address;
}

house myStreet = new house[5];

myStreet[2]->people = 1;
myStreet[4]->address = new char[strlen((const char *)"4 Subdene")  + 1];

strcpy(myStreet[4]->address, "4 Subdene");
myStreet[4]->address[0] = '5';

Something like that?

[The Dog]

Lets say that i defined a structure as follows :

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

struct Person
{
       char* name;
       char* surname;
};

...

int main()
{
       struct Person  student[20];
       struct Person*ptrStudent;
       int i;
       ptrStudent = student;             //Initialize the pointer
       
       for(i=0;i<20;i++)
       {
            ptrStudent[i]->name = (char*)malloc(20);
            ptrStudent[i]->surname = (char*)malloc(20);
       }
       
       return 0;
}

"ptrStudent[i]->name" is the same as saying
"(*ptrStudent[i]).name" or it should be.

[subdene]

Thanks, for your replies, thats helped alot. Dual just one quick question. In this section of code when you are assigning the length of the variable,

myStreet[4]->address = new char[strlen((const char *)"4 Subdene")];

why can't you do:-

myStreet[4]->address = new char[strlen("4 Subdene")];

don't fully understand what the const char is there for.

Thanks.

[Salem]

Since a "string" is already a const char *, it seems entirely redundant to say it

Besides, it's needs to be
myStreet[4]->address = new char[ strlen("4 Subdene") + 1 ];

Gotta remember to add space for that all important \0 at the end of the string

[borko_b]

this thing below is wrong ...

       struct Person*ptrStudent;
       for(i=0;i<20;i++)
       {
            ptrStudent[i]->name = (char*)malloc(20);
            ptrStudent[i]->surname = (char*)malloc(20);
       }

it should be :

       struct Person*ptrStudent;
       for(i=0;i<20;i++)
       {
            ptrStudent[i].name = (char*)malloc(20);
            ptrStudent[i].surname = (char*)malloc(20);
       }

the subscript operator
here
ptrStudent[i]
access the value pointed by ptrStudent
and this value is NOT a pointer !
so using '->' (access fields by pointer) is wrong.
it should be '.' (access fields by value/object)

be carefull what you write ...

[subdene]

I have been declaring the pointer to the structure a different way.

struct House
{
  //whatever
};

House* Street;

Street = new House[NUM_HOUSES];

is this wrong?

[golfinguy4]

Nope.

[subdene]

Well everytime I try to access a member i get the following error:

[C++ Error] New.cpp(48): E2288 Pointer to structure required on left side of -> or ->*

#include <iostream.h>

const int MAX_ADDRESS=50;

struct House
{
  int NumWindows;
  char Address[MAX_ADDRESS];
};

int main(void)
{
  const int NUM_HOUSES=5;
  
  House *Street;

  Street = new House[NUM_HOUSES];

  strcpy(Street[1]->Address, "22 Holgate rd\0");

  cout << Street[1]->Address;
  getchar();

  return 0;
}

[subdene]

Can someome have a quick look at the problem, I can't go any further until this is resolved.

[moemen ahmed]

here we go.....hope it ll work as u would like.........
--------------------------------------------------------------------------------
#include <iostream.h>
#include <conio.h>
const int MAX_ADDRESS=50;

struct House
{
int NumWindows;
char Address[MAX_ADDRESS];
};

int main(void)
{
const int NUM_HOUSES=5;

House* Street= new House[NUM_HOUSES];

strcpy(Street[1].Address, "22 Holgate rd\0");

cout << Street[1].Address;
getche();

return 0;
}

[subdene]

Thanks, for the reply. That got the problem sorted. How come I did not have to use the -> operator, as I delcared a pointer to an object?

[moemen ahmed]

thats because yr using (ARRAY) of the strucure, so u ve to use the (.) while u ve to use ( ->) if ur using a pointer to single structure.

[subdene]

Ta, thanks for everyones help.