need help with string

[puzzlecracker]

let's say have a string: string str="arg1 arg2 arg3";

I need to convert it to

char **s where s={arg1, arg2,arg3, NULL};
has anyone encountered this problem and has fast solution?

Thanks

[Vimal Aravindashan]

puzzlecracker wrote:

let's say have a string: string str="arg1 arg2 arg3";

I need to convert it to

char **s where s={arg1, arg2,arg3, NULL};
has anyone encountered this problem and has fast solution?

Thanks

If you have tried something to get it done, post your code, and you'll
get help.
If you are trying to get someone else to do your work, you are just
another ... I'll reserve my comments. :-)

Anyway, here's are a couple of tips.
1) string's c_str() returns a non-modifiable C string, so use copy()
instead.
2) Replace the spaces with '\0' to "create" separate strings out of the
copied string.

Hope this helps...

Rgds,
Vimal.
--
"If you would be a real seeker after truth, it is necessary that at
least once in your life you doubt, as far as possible, all things."
-- Rene Descartes

[Someonekicked]

most direct way ( there might be easier way),
#include <iostream>

#include <sstream>

#include <string>

using namespace std;

int main()

{

string str="arg1 arg2 arg3";

stringstream ss;

char **s;

int count_space = str.size() == 0 ? 0 : 1; // cover the case of empty
string

for(int i = 0; i < str.size(); i++)

{

if (str[i] == ' ')

count_space++;

}

s = new char * [count_space + 1];

s[count_space] = NULL;
ss << str;

for(int i = 0; ss >> str; i++)

{

s[i] = new char[str.length() + 1];

strncpy(s[i],str.data(),str.length());

s[i][str.length()] = '\0';

}

return 0;

}

"puzzlecracker" <ir*********@gmail.com> wrote in message
news:11**********************@g49g2000cwa.googlegr oups.com...

let's say have a string: string str="arg1 arg2 arg3";

I need to convert it to

char **s where s={arg1, arg2,arg3, NULL};
has anyone encountered this problem and has fast solution?

Thanks

[Mike Wahler]

"puzzlecracker" <ir*********@gmail.com> wrote in message
news:11**********************@g49g2000cwa.googlegr oups.com...

let's say have a string: string str="arg1 arg2 arg3";

I need to convert it to

char **s where s={arg1, arg2,arg3, NULL};
has anyone encountered this problem and has fast solution?

#include <iostream>
#include <string.h>

int main()
{
const char *data = "arg1 arg2 arg3";
char *a[sizeof data / sizeof *data + 1] =
{
strstr(data, "arg1"),
strstr(data, "arg2"),
strstr(data, "arg3")
};

char **s = a;

size_t i = 0;

while(s[i])
{
for(size_t j = 0; j < 4; ++j)
std::cout.put(s[i][j]);

std::cout.put('\n');
++i;
}

return 0;
}

This was the fastest way I could write it.

("Useful?", now that's a different story. :-))

-Mike

[puzzlecracker]

Vimal Aravindashan wrote:

puzzlecracker wrote:

let's say have a string: string str="arg1 arg2 arg3";

I need to convert it to

char **s where s={arg1, arg2,arg3, NULL};
has anyone encountered this problem and has fast solution?

Thanks

If you have tried something to get it done, post your code, and you'll
get help.
If you are trying to get someone else to do your work, you are just
another ... I'll reserve my comments. :-)

Anyway, here's are a couple of tips.
1) string's c_str() returns a non-modifiable C string, so use copy()
instead.
2) Replace the spaces with '\0' to "create" separate strings out of the
copied string.

Hope this helps...

Rgds,
Vimal.
--
"If you would be a real seeker after truth, it is necessary that at
least once in your life you doubt, as far as possible, all things."
-- Rene Descartes

string args= "srcipt arg1 arg2 arg3..."
.....

int size=args.size()*2; // to make sure I have enough room
char *argvec=new char[size];
memset(argvec,'\0',size);
args.copy(argvec,size);

pid_t pid;
if(pid=fork()<0)
{
cerr<<"failed in fork(), exit 1\n";
exit(1);

}
else if(pid==0)
{
if(execv("/home/work/bin/script",&argvec)<0)
{
cerr<<"failed in execv, exit 1\n";
exit(1);
}
}
.....
for some reason execv failed.. any ideas?

ffaialed in execv, exit 1
iled in execv, exit 1
with

[puzzlecracker]

Someonekicked wrote:

most direct way ( there might be easier way),
#include <iostream>

#include <sstream>

#include <string>

using namespace std;

int main()

{

string str="arg1 arg2 arg3";

stringstream ss;

char **s;

int count_space = str.size() == 0 ? 0 : 1; // cover the case of empty
string

for(int i = 0; i < str.size(); i++)

{

if (str[i] == ' ')

count_space++;

}

s = new char * [count_space + 1];

s[count_space] = NULL;
ss << str;

for(int i = 0; ss >> str; i++)

{

s[i] = new char[str.length() + 1];

strncpy(s[i],str.data(),str.length());

s[i][str.length()] = '\0';

}

return 0;

}

Thanks, might not work, you forgetting issue about tabs

[Vimal Aravindashan]

puzzlecracker wrote:

Vimal Aravindashan wrote:

puzzlecracker wrote:

let's say have a string: string str="arg1 arg2 arg3";

I need to convert it to

char **s where s={arg1, arg2,arg3, NULL};

Anyway, here's are a couple of tips.
1) string's c_str() returns a non-modifiable C string, so use copy()
instead.
2) Replace the spaces with '\0' to "create" separate strings out of the
copied string.

string args= "srcipt arg1 arg2 arg3..."
.....

int size=args.size()*2; // to make sure I have enough room

No need. args.size() will do just fine.
char *argvec=new char[size];
memset(argvec,'\0',size); No need for this memset either.
args.copy(argvec,size);
Its okay till here. After you find out how many args are there (n), this
is what you need to do:
NOTE: following code was not tested, so use it more like pseudocode

char **sz;
sz = new (char *)[n+1]; // you need a NULL at the end, right?

sz[0] = &argvec[0]; // sz[0] will hold only the first arg (you'll see)

c = 1; // we already have the first arg

for(int i=0; i<args.length(); i++) {
if(argvec[i]==' ') {
sz[c++] = &argvec[i+1]; // the remaining args

argvec[i] = '\0'; // replacing the space with '\0', makes each one
separate.
}
}
sz[c] = NULL; // the final NULL

The remaining code has nothing to do with C++. Try a different newsgroup.
Cheers,
Vimal.
pid_t pid;
if(pid=fork()<0)
{
cerr<<"failed in fork(), exit 1\n";
exit(1);

}
else if(pid==0)
{
if(execv("/home/work/bin/script",&argvec)<0)
{
cerr<<"failed in execv, exit 1\n";
exit(1);
}
}
.....
for some reason execv failed.. any ideas?

ffaialed in execv, exit 1
iled in execv, exit 1
with

--
"If you would be a real seeker after truth, it is necessary that at
least once in your life you doubt, as far as possible, all things."
-- Rene Descartes

[Kai-Uwe Bux]

puzzlecracker wrote:

Someonekicked wrote:

most direct way ( there might be easier way),
#include <iostream>

#include <sstream>

#include <string>

using namespace std;

int main()

{

string str="arg1 arg2 arg3";

stringstream ss;

char **s;

int count_space = str.size() == 0 ? 0 : 1; // cover the case of empty
string

for(int i = 0; i < str.size(); i++)

{

if (str[i] == ' ')

count_space++;

}

s = new char * [count_space + 1];

s[count_space] = NULL;
ss << str;

for(int i = 0; ss >> str; i++)

{

s[i] = new char[str.length() + 1];

strncpy(s[i],str.data(),str.length());

s[i][str.length()] = '\0';

}

return 0;

}

Thanks, might not work, you forgetting issue about tabs

What about:

#include <string>
#include <vector>
#include <sstream>
#include <iostream>

typedef char* c_string;
typedef c_string* c_string_array;

c_string to_c_string ( std::string const & str ) {
// you own the result, you have to delete it.
// use delete [] to get rid of that crap.
c_string result = new char [ str.size() + 1 ];
std::string::size_type i;
for ( i = 0; i < str.size(); ++i ) {
result[i] = str[i];
}
result[i] = 0;
return( result );
}

c_string_array chop ( std::string const & str ) {
// you own the result, you have to delete it.
// use delete [] to get rid of that crap.
// BEWARE: you have to get rid of the c_strings therein first.
std::istringstream istr ( str );
std::string arg;
std::vector< c_string > dummy;
while ( istr >> arg ) {
dummy.push_back( to_c_string( arg ) );
}
c_string_array result = new c_string [ dummy.size() + 1 ];
std::vector< c_string >::size_type i;
for ( i = 0; i < dummy.size(); ++i ) {
result[i] = dummy[i];
}
result[i] = 0;
return ( result );
}

int main ( void ) {
std::string line ( "ab cd efg" );
c_string_array arr = chop ( line );
for ( c_string* str_ptr = arr; *str_ptr != 0; ++str_ptr ) {
std::cout << *str_ptr << '\n';
delete *str_ptr;
}
delete arr;
}

Best

Kai-Uwe Bux

[Dave Townsend]

"puzzlecracker" <ir*********@gmail.com> wrote in message
news:11**********************@g49g2000cwa.googlegr oups.com...

let's say have a string: string str="arg1 arg2 arg3";

I need to convert it to

char **s where s={arg1, arg2,arg3, NULL};
has anyone encountered this problem and has fast solution?

Thanks

You've not been reading recent posts, redfloyd posted a similar solution
which
I've shamelessly adapted....Of course, you might use strtok() to token your
original
string & create the array of what-have-yous.

#include <string>
#include <sstream>
#include <iterator>
#include <vector>
int main(int argc, char* argv[])
{

char* ARGS[100];
int ARGSC = 0;

std::istringstream is(" arg1 arg2 arg3 arg4 arg5 " );
for ( std::istream_iterator<std::string> it(is) ;
it!=std::istream_iterator<std::string>() ; ++it, ++ARGSC)
{
std::string s=*it;
ARGS[ARGSC]= strdup( s.c_str() );
}
return 0;

}

[puzzlecracker]

Dave Townsend wrote:

"puzzlecracker" <ir*********@gmail.com> wrote in message
news:11**********************@g49g2000cwa.googlegr oups.com...

let's say have a string: string str="arg1 arg2 arg3";

I need to convert it to

char **s where s={arg1, arg2,arg3, NULL};
has anyone encountered this problem and has fast solution?

Thanks

You've not been reading recent posts, redfloyd posted a similar solution
which
I've shamelessly adapted....Of course, you might use strtok() to token your
original
string & create the array of what-have-yous.

#include <string>
#include <sstream>
#include <iterator>
#include <vector>
int main(int argc, char* argv[])
{

char* ARGS[100];
int ARGSC = 0;

std::istringstream is(" arg1 arg2 arg3 arg4 arg5 " );
for ( std::istream_iterator<std::string> it(is) ;
it!=std::istream_iterator<std::string>() ; ++it, ++ARGSC)
{
std::string s=*it;
ARGS[ARGSC]= strdup( s.c_str() );
}
return 0;

}

Almost all of your solutions expose a notorious problem in c++
community that has rather horrid and sadistic ramifications. That
problem is memory leak. Would anyone suggest a solution where we don't
have to deal with memory - at least directly to solve this problem?
Ps. I said'some' because they only need one for loop to solve it.
ps2. I hate mixing c and c++ - the task for fearless and
ready-to-explain-your-boss-why-component-fucks-up.

[Branimir Maksimovic]

"puzzlecracker" <ir*********@gmail.com> wrote in message
news:11**********************@g44g2000cwa.googlegr oups.com...

puzzlecracker wrote:

> let's say have a string: string str="arg1 arg2 arg3";
>
> I need to convert it to
>
> char **s where s={arg1, arg2,arg3, NULL};
>
>
> has anyone encountered this problem and has fast solution?
>
> Thanks
>

string args= "srcipt arg1 arg2 arg3..."
.....

int size=args.size()*2; // to make sure I have enough room
char *argvec=new char[size];
memset(argvec,'\0',size);
args.copy(argvec,size);

vector<char*> argv;
string a ="script arg1 arg2 arg3";
vector<char> args(a.begin(),a.end());
args.push_back(' ');
while(vector<char>::iterator i=args.begin(),j=args.end();i!=args.end();)
{
vector<char>::iterator k = find(i,j,' ');
*k = 0;
argv.push_back(&*i);
i=++k;
}
argv.push_back(0);
pid_t pid;
if(pid=fork()<0)
{
cerr<<"failed in fork(), exit 1\n";
exit(1);

}
else if(pid==0)
{
if(execv("/home/work/bin/script",&argvec)<0) if(execv("/home/work/bin/script",&argv[0])<0) {
cerr<<"failed in execv, exit 1\n";
exit(1);
}
}
.....
for some reason execv failed.. any ideas?

You didn't pass array of pointers to char.

Greetings, Bane.

[Branimir Maksimovic]

"Branimir Maksimovic" <bm***@eunet.yu> wrote in message
news:di**********@news.eunet.yu...

while(vector<char>::iterator i=args.begin(),j=args.end();i!=args.end();)

should be
for(vector<char>::iterator i=args.begin(),j=args.end();i!=args.end();)

[Dave Townsend]

The memory has to be allocated somewhere Sunshine, you'll have
to figure out how to release it when you're done. Alternatively, you
can restate your problem to use strings instead of char*.
"puzzlecracker" <ir*********@gmail.com> wrote in message
news:11**********************@g47g2000cwa.googlegr oups.com...

Dave Townsend wrote:

"puzzlecracker" <ir*********@gmail.com> wrote in message
news:11**********************@g49g2000cwa.googlegr oups.com...

let's say have a string: string str="arg1 arg2 arg3";

I need to convert it to

char **s where s={arg1, arg2,arg3, NULL};
has anyone encountered this problem and has fast solution?

Thanks

You've not been reading recent posts, redfloyd posted a similar solution
which
I've shamelessly adapted....Of course, you might use strtok() to token your original
string & create the array of what-have-yous.

#include <string>
#include <sstream>
#include <iterator>
#include <vector>
int main(int argc, char* argv[])
{

char* ARGS[100];
int ARGSC = 0;

std::istringstream is(" arg1 arg2 arg3 arg4 arg5 " );
for ( std::istream_iterator<std::string> it(is) ;
it!=std::istream_iterator<std::string>() ; ++it, ++ARGSC)
{
std::string s=*it;
ARGS[ARGSC]= strdup( s.c_str() );
}
return 0;

}

Almost all of your solutions expose a notorious problem in c++
community that has rather horrid and sadistic ramifications. That
problem is memory leak. Would anyone suggest a solution where we don't
have to deal with memory - at least directly to solve this problem?
Ps. I said'some' because they only need one for loop to solve it.
ps2. I hate mixing c and c++ - the task for fearless and
ready-to-explain-your-boss-why-component-fucks-up.