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Re: String and std::string

On Fri, 2003-03-21 at 23:12, Alex Tibbles wrote:
> <snip>
> > I don't care whether you use std::string, or
> > String++ for any new code,
> > as long as:
> > 1) You don't leak memory (std::string will leak if
> > you use c_str())
> > IIRC.
> I've been unable to confirm this. I tried the attached
> program (compiled with gcc -lstdc++ stringleak.cpp)
> and got the following results from top: 

Well, your test is flawed for the behaviour I was referring to. A new
one is below.

>   648 alex      14   0   556  556   416 R    56.2  0.2
> 3:02 a.out
> Am I correct in concluding that std::string::c_str()
> does not leak? I'm interested as I use c_str() a fair
> amount for interfacing C++ with C (I believe that was
> what it was designed for, but I'm only guessing).
> ______________________________________________________________________
> #include <string>
> #include <iostream>
> int main()
> {
> 	std::string bleg("bleg");
> 	while (true)
> 	{
> 		std::cout << bleg.c_str();
> 	}
> 	return 0;
> }

the above won't leak, because c_str() returns the internal buffer -
which isn't being altered.

this may well. Look in the g++ library for freeze() (again, IIRC). The
thing I saw when I was reading the source, was that the internal buffer
was not delete[]'d once it was handed out via c_str(). That was with the
libstc++ for gcc 2.95 as well. I've just checked the g++ 3
implementation, and it's different to what I recall from before...

#include <string>
#include <iostream>

int main ()
while (true)
   std::string foo("bar");
   char const *leakingpointer = foo.c_str();
 return 0;
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