Read memory buffer via stream interface

[Steven Woody]

Hi,

for example, i have

unsigned char buff[ 100 ]

the buffer hold a sequences of raw bytes. My question is, what is the
standard method of reading the `buff' via std::istream interface?

A relative question is: how to write to the `buff' via std::ostream
interface? I think this can be done by using std::stringstream, but i
am not sure of it.

Thanks.

-
woody

[kasthurirangan.balaji]

On Mar 5, 2:16*pm, Steven Woody <[e-mail]:

Hi,

for example, i have

* unsigned char buff[ 100 ]

the buffer hold a sequences of raw bytes. *My question is, what is the
standard method of reading the `buff' via std::istream interface?

A relative question is: how to write to the `buff' via std::ostream
interface? I think this can be done by using std::stringstream, but i
am not sure of it.

Thanks.

-
woody

Use std::istringstream for input, std::ostringstream for output,
std::stringstream for both. Once you have created a stringstream, you
can use istream/ostream read/write facilities on it.

#include <iostream>
#include <cstring>
#include <sstream>

main()
{
std::stringstream sstr;
sstr << "balaji";
std::cout << sstr.str() << '\n';
sstr.str(""); //clear in-memory data
char buf[100];
strcpy(buf,"asdkjabvdba");
std::stringstream sstr1(buf);
std::cout << sstr1.str() << '\n';
}

Thanks,
Balaji.

[Steven Woody]

On Mar 5, 5:38 pm, [e-mail] wrote:

On Mar 5, 2:16 pm, Steven Woody <[e-mail]:

Hi,

for example, i have

unsigned char buff[ 100 ]

the buffer hold a sequences of raw bytes. My question is, what is the
standard method of reading the `buff' via std::istream interface?

A relative question is: how to write to the `buff' via std::ostream
interface? I think this can be done by using std::stringstream, but i
am not sure of it.

Thanks.

-
woody

Use std::istringstream for input, std::ostringstream for output,
std::stringstream for both. Once you have created a stringstream, you
can use istream/ostream read/write facilities on it.

#include <iostream>
#include <cstring>
#include <sstream>

main()
{
std::stringstream sstr;
sstr << "balaji";
std::cout << sstr.str() << '\n';
sstr.str(""); //clear in-memory data
char buf[100];
strcpy(buf,"asdkjabvdba");
std::stringstream sstr1(buf);
std::cout << sstr1.str() << '\n';

}

Thanks,
Balaji.

Thanks a lot! I just did not see that a stringstream can be
constructed from a char[]. My book does not mentioned that. Where's
a good STL reference I can find online or free?

Another question I also like to ask here:

After,
char buf[100];
strcpy(buf,"123\n");
std::stringstream sstr1(buf);

How can I let cout << sstr1.str() << endl; prints something like that:

0x31 0x32 0x33 0x0a ?

Thanks again.

-
woody

[kasthurirangan.balaji]

On Mar 5, 4:57*pm, Steven Woody <[e-mail]:

On Mar 5, 5:38 pm, [e-mail] wrote:

On Mar 5, 2:16 pm, Steven Woody <[e-mail]:

Hi,

for example, i have

* unsigned char buff[ 100 ]

the buffer hold a sequences of raw bytes. *My question is, what is the
standard method of reading the `buff' via std::istream interface?

A relative question is: how to write to the `buff' via std::ostream
interface? I think this can be done by using std::stringstream, but i
am not sure of it.

Thanks.

-
woody

Use std::istringstream for input, std::ostringstream for output,
std::stringstream for both. Once you have created a stringstream, you
can use istream/ostream read/write facilities on it.

#include <iostream>
#include <cstring>
#include <sstream>

main()
{
std::stringstream sstr;
sstr << "balaji";
std::cout << sstr.str() << '\n';
sstr.str(""); //clear in-memory data
char buf[100];
strcpy(buf,"asdkjabvdba");
std::stringstream sstr1(buf);
std::cout << sstr1.str() << '\n';

}

Thanks,
Balaji.

Thanks a lot! *I just did not see that a stringstream can be
constructed from a char[]. *My book does not mentioned that. *Where's
a good STL reference I can find online or free?

Another question I also like to ask here:

After,
* char buf[100];
* strcpy(buf,"123\n");
* std::stringstream sstr1(buf);

How can I let cout << sstr1.str() << endl; prints something like that:

* 0x31 0x32 0x33 0x0a ?

Thanks again.

-
woody- Hide quoted text -

- Show quoted text -

You may want to use this.

#include <iostream>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <string>

void print(const char &c)
{
std::cout << std::showbase << std::hex << toascii(c) << ' ';
}

main()
{
std::stringstream sstr;
sstr << "balaji";
std::cout << sstr.str() << '\n';
sstr.str(""); //clear data
char buf[100];
strcpy(buf,"123\n");
std::stringstream sstr1(buf);
std::cout << sstr1.str() << '\n';
const std::string &temp(sstr1.str());
std::for_each(temp.begin(),temp.end(),print);
}
You may also try for ebooks of C++ primer and The C++ Standard Library
by Josuttis.

Thanks,
Balaji.

[James Kanze]

On Mar 5, 2:12 pm, [e-mail] wrote:

On Mar 5, 4:57 pm, Steven Woody <[e-mail]:

[...]

You may want to use this.

#include <iostream>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <string>

void print(const char &c)
{
std::cout << std::showbase << std::hex << toascii(c) << ' ';

What's "toascii"? The only "toascii" I know of is a very old
pre-standard C Unix function---from the days when isupper, etc.
only worked for ASCII characters.

(It's also considered good practice to restore the flags of an
output stream after modifying them. You don't necessarily want
all of the output in the rest of the program to be in hex.)

}

main()

And of course, you'll need to declare main to return an int.

{
std::stringstream sstr;
sstr << "balaji";
std::cout << sstr.str() << '\n';
sstr.str(""); //clear data
char buf[100];
strcpy(buf,"123\n");
std::stringstream sstr1(buf);
std::cout << sstr1.str() << '\n';
const std::string &temp(sstr1.str());

Why the reference here?

std::for_each(temp.begin(),temp.end(),print);
}

--
James Kanze (GABI Software) email:ja*********@gmail.com
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, [phone]

[kasthurirangan.balaji]

On Mar 5, 6:49*pm, James Kanze <[e-mail]:

On Mar 5, 2:12 pm, [e-mail] wrote:

On Mar 5, 4:57 pm, Steven Woody <[e-mail]:

* * [...]

You may want to use this.

#include <iostream>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <string>
void print(const char &c)
{
* * * * std::cout << std::showbase << std::hex << toascii(c) << ' ';

What's "toascii"? *The only "toascii" I know of is a very old
pre-standard C Unix function---from the days when isupper, etc.
only worked for ASCII characters.

yes, i know. may i know whats its replacement?

(It's also considered good practice to restore the flags of an
output stream after modifying them. *You don't necessarily want
all of the output in the rest of the program to be in hex.)

definitely yes, thought OP might include that as part of his
requirement.

}
main()

And of course, you'll need to declare main to return an int.

agreed.

{
std::stringstream sstr;
sstr << "balaji";
std::cout << sstr.str() << '\n';
sstr.str(""); //clear data
char buf[100];
strcpy(buf,"123\n");
std::stringstream sstr1(buf);
std::cout << sstr1.str() << '\n';
const std::string &temp(sstr1.str());

Why the reference here?

i thought of using sstr1.str().begin() - which i am not sure whether
it would work or not. By making const and reference(to a temporary), i
went ahead with the below. If wrong, pls correct.

std::for_each(temp.begin(),temp.end(),print);
}

--
James Kanze (GABI Software) * * * * * * email:[e-mail]
Conseils en informatique orientée objet/
* * * * * * * * * *Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, [phone]

Thanks,
Balaji.

[Steven Woody]

On Mar 5, 9:12 pm, [e-mail] wrote:

On Mar 5, 4:57 pm, Steven Woody <[e-mail]:

On Mar 5, 5:38 pm, [e-mail] wrote:

On Mar 5, 2:16 pm, Steven Woody <[e-mail]:

Hi,

for example, i have

unsigned char buff[ 100 ]

the buffer hold a sequences of raw bytes. My question is, what is the
standard method of reading the `buff' via std::istream interface?

A relative question is: how to write to the `buff' via std::ostream
interface? I think this can be done by using std::stringstream, but i
am not sure of it.

Thanks.

-
woody

Use std::istringstream for input, std::ostringstream for output,
std::stringstream for both. Once you have created a stringstream, you
can use istream/ostream read/write facilities on it.

#include <iostream>
#include <cstring>
#include <sstream>

main()
{
std::stringstream sstr;
sstr << "balaji";
std::cout << sstr.str() << '\n';
sstr.str(""); //clear in-memory data
char buf[100];
strcpy(buf,"asdkjabvdba");
std::stringstream sstr1(buf);
std::cout << sstr1.str() << '\n';

}

Thanks,
Balaji.

Thanks a lot! I just did not see that a stringstream can be
constructed from a char[]. My book does not mentioned that. Where's
a good STL reference I can find online or free?

Another question I also like to ask here:

After,
char buf[100];
strcpy(buf,"123\n");
std::stringstream sstr1(buf);

How can I let cout << sstr1.str() << endl; prints something like that:

0x31 0x32 0x33 0x0a ?

Thanks again.

-
woody- Hide quoted text -

- Show quoted text -

You may want to use this.

#include <iostream>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <string>

void print(const char &c)
{
std::cout << std::showbase << std::hex << toascii(c) << ' ';

}

main()
{
std::stringstream sstr;
sstr << "balaji";
std::cout << sstr.str() << '\n';
sstr.str(""); //clear data
char buf[100];
strcpy(buf,"123\n");
std::stringstream sstr1(buf);
std::cout << sstr1.str() << '\n';
const std::string &temp(sstr1.str());
std::for_each(temp.begin(),temp.end(),print);

}

You may also try for ebooks of C++ primer and The C++ Standard Library
by Josuttis.

Thanks,
Balaji.

Thank you Balaji!