Dynamic sized structs

[Jonathan Halterman]

I have data that is coming in from a network stream which I would like to
format into a struct, but I do not know the size of all the pieces of the
struct until I receive the data, so I cannot simply cast the data into my
struct as I would normally do with organized network data. The data I am
receiving looks something like this:

long lvalue1
long lvalue2
char flag
long data1len //size of data1
unsigned char data1[x]
long data2len //size of data2
unsigned char data2[x]
long data3len //size of data3
unsigned char data3[x]

If I have a pointer to the data all together, how can I separate it based on
the structure above, correctly sizing each of the data charater arrays?

thanks
jonathan

[E. Robert Tisdale]

Re: Dynamic sized structs

Jonathan Halterman wrote:
[color=blue]
> I have data that is coming in from a network stream which I would like to
> format into a struct, but I do not know the size of all the pieces of the
> struct until I receive the data, so I cannot simply cast the data into my
> struct as I would normally do with organized network data. The data I am
> receiving looks something like this:[/color]

class Data {
private:
long lvalue1;
long lvalue2;
char flag;
long data1len; //size of data1
unsigned char* data1;
long data2len; //size of data2
unsigned char* data2;
long data3len; //size of data3
unsigned char* data3;
public:
Data(void): lvalue1(0), lvalue2(0), flag('\0'),
data1len(0), data1(0),
data2len(0), data2(0),
data3len(0), data3(0) { }
Data(const Data& d);
Data& operator=(const Data& d);
~Data(void) {
delete [] data1;
delete [] data2;
delete [] data3;
}
Data& receive(instrea m& ins) {
ins >> lvalue1 >> lvalue2 >> flag >> data1len;
data1 = new char[data1len];
for (long j = 0; j < data1len; ++j)
ins >> data1[j];
ins >> data2len;
data2 = new char[data2len];
for (long j = 0; j < data2len; ++j)
ins >> data2[j];
ins >> data3len;
data3 = new char[data3len];
for (long j = 0; j < data3len; ++j)
ins >> data3[j];
return *this;
}
};

[color=blue]
> If I have a pointer to the data all together, how can I separate it based on
> the structure above, correctly sizing each of the data character arrays?[/color]

[Jonathan Halterman]

Re: Dynamic sized structs

This is excellent. Thanks Robert.


"E. Robert Tisdale" <E.Robert.Tisda le@jpl.nasa.gov > wrote in message
news:3F8C844E.5 030804@jpl.nasa .gov...[color=blue]
> Jonathan Halterman wrote:
>[color=green]
> > I have data that is coming in from a network stream which I would like[/color][/color]
to[color=blue][color=green]
> > format into a struct, but I do not know the size of all the pieces of[/color][/color]
the[color=blue][color=green]
> > struct until I receive the data, so I cannot simply cast the data into[/color][/color]
my[color=blue][color=green]
> > struct as I would normally do with organized network data. The data I am
> > receiving looks something like this:[/color]
>
> class Data {
> private:
> long lvalue1;
> long lvalue2;
> char flag;
> long data1len; //size of data1
> unsigned char* data1;
> long data2len; //size of data2
> unsigned char* data2;
> long data3len; //size of data3
> unsigned char* data3;
> public:
> Data(void): lvalue1(0), lvalue2(0), flag('\0'),
> data1len(0), data1(0),
> data2len(0), data2(0),
> data3len(0), data3(0) { }
> Data(const Data& d);
> Data& operator=(const Data& d);
> ~Data(void) {
> delete [] data1;
> delete [] data2;
> delete [] data3;
> }
> Data& receive(instrea m& ins) {
> ins >> lvalue1 >> lvalue2 >> flag >> data1len;
> data1 = new char[data1len];
> for (long j = 0; j < data1len; ++j)
> ins >> data1[j];
> ins >> data2len;
> data2 = new char[data2len];
> for (long j = 0; j < data2len; ++j)
> ins >> data2[j];
> ins >> data3len;
> data3 = new char[data3len];
> for (long j = 0; j < data3len; ++j)
> ins >> data3[j];
> return *this;
> }
> };
>
>[color=green]
> > If I have a pointer to the data all together, how can I separate it[/color][/color]
based on[color=blue][color=green]
> > the structure above, correctly sizing each of the data character arrays?[/color]
>
>[/color]