osstream and stuff

[grahamo]

Hi,

Can anybody tell me why I sometimes see an integer value when I try to
print the "out" variable below and if I coerce it into a (char*), I
see the string "hello" as expected. The str() member function returns
a char* so I would have thout there was no coercing needed. ???

char* in = strdup("hello");
strstream input(in, strlen(in);
input << std::ends;


cout << "stream contains " << input.str() << endl;

char* out = strdup(output.str());

cout << "out is " << out << endl;
cout << "out is " << (char*) out << endl;



thanks a million


GrahamO

 

[Buster]

Can anybody tell me why I sometimes see an integer value when I try to
print the "out" variable below and if I coerce it into a (char*), I
see the string "hello" as expected. The str() member function returns
a char* so I would have thout there was no coercing needed. ???

(i) What platform? What compiler? What version?
(ii) Post a complete program.
(iii) Don't use strstream, it's deprecated.
(iv) Don't use strdup, it's nonstandard.

 

[Christopher Benson-Manica]

char* in = strdup("hello");

1) Use std::strings, not strdup().
2) const char *in="hello", not strdup().
3) If you insist on using strdup() anyway, realize that you are
responsible for free()'ing the memory when you're done with it.

strstream input(in, strlen(in);
input << std::ends;

cout << "stream contains " << input.str() << endl;

char* out = strdup(output.str());

You omitted your declaration of output - what is it? If output is an
ostringstream (or perhaps osstream), str() is a std::string - not a const
char *, which is what strdup expects.

char *out=strdup( output.str().c_str() );

cout << "out is " << out << endl;
cout << "out is " << (char*) out << endl;

If you quit trying to use strdup() and C-style strings, your life will
become easier.

 

[John Harrison]

Hi,

Can anybody tell me why I sometimes see an integer value when I try to
print the "out" variable below and if I coerce it into a (char*), I
see the string "hello" as expected. The str() member function returns
a char* so I would have thout there was no coercing needed. ???

What the str() member function produces is of no relevance.

char* in = strdup("hello");
strstream input(in, strlen(in);
input << std::ends;


cout << "stream contains " << input.str() << endl;

char* out = strdup(output.str());

cout << "out is " << out << endl;
cout << "out is " << (char*) out << endl;

That should never make any difference because out already is char* so
casting it can make no difference. Suggest you produce a complete compilable
program that consistently produces this error. Then post it here.

john