Re: structures and pointers

From:

"John Carson" <jcarson_n_o_sp_am_@netspace.net.au>

Newsgroups:

microsoft.public.vc.language

Date:

Wed, 27 Sep 2006 15:13:42 +1000

Message-ID:

<#DBXIPf4GHA.3740@TK2MSFTNGP02.phx.gbl>

"www.fruitfruit.com" <no_email@fruitfruit.com> wrote in message
news:Onf1rte4GHA.1252@TK2MSFTNGP04.phx.gbl

nemesia31@gmail.com wrote:

i have a structure
typedef struct tm
{
int date;
int hour;
int minutes;
} time;

i want to use this structure dynamically, ie, i want it to grow.

like it would be
time *sept= new time;
sept->date=15;
.....
........
......
but i want something like

for(int i=0;i<MAX;i++)
{
sept[i]->date=i+5;
}

i want to grow the structure dynamically, ie, the valur of MAX is
provided at runtime.
how can i do tht????

Use STL container
#include <deque>
std::deque<*time> time_collection;
for(int i=0; i< MAX; i++)
{
time_collection.push_back( new time );
time_collection[i]->date = i+5;
}

Your collection isn't buying you anything here since you will still need to
manually delete the memory allocated. You could achieve the same effect
with:

#include <iostream>
using namespace std;

struct Time
{
    int date;
    int hour;
    int minutes;
};

int main()
{
    int MAX;
    cin >> MAX;
    Time *sept= new Time[MAX];

    for(int i=0;i<MAX;i++)
    {
        sept[i].date=i+5;
    }
    // later
    delete [] sept;

    return 0;
}

Alternatively, you could use a container to avoid manual memory allocation.

#include <iostream>
#include <vector>
using namespace std;

struct Time
{
    int date;
    int hour;
    int minutes;
};

int main()
{
    int MAX;
    cin >> MAX;
    vector<Time> sept(MAX, Time());

    for(int i=0;i<MAX;i++)
    {
        sept[i].date=i+5;
    }
    // no delete required

    return 0;
}

If the size of MAX may change during the running of the program, then the
member functions resize() or, as you indicated, push_back() may be used.

--
John Carson