Re: does std::string have something like CString::GetBuffer?

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Sat, 31 May 2008 02:47:10 -0700 (PDT)
Message-ID:
<687a0da1-0886-43d3-b9f1-2059e9ac266c@27g2000hsf.googlegroups.com>
On May 31, 9:40 am, Kai-Uwe Bux <jkherci...@gmx.net> wrote:

Sam wrote:

sas writes:

c_str doesn't work for me, because it returns a const, i
want to be able to pass the raw zero-terminated buffer to a
C function that changes it, then tell the string object to
update with the new sequence.


There is no equivalent functionality in std::string. You
can achieve the same functionality by using the append()
method to resize the string to the required size, and then
using std::string's iterators to mess around with its
contents.

I know what you're talking about, and there is no direct
equivalent in std::string, and it's a good thing. MFC's
sloppy class design opens many opportunities for coding
errors, like buffer overflows and stack smashing, that leads
to security holes. You will find out that using the C++
library and STL containers correctly leads to good
programming practices that eliminates nearly all
opportunities for coding errors of this nature.


I am not so sure whether std::string is well designed in this
regard. As far as I can see,

  str[huge_number] = 'c';

is just as prone to buffer overflows and stack corruption as
anything else.


It's a quality of implementation issue. With the better
implementations I use (g++, VC++), this will cause a program
crash. With the poorer ones, it will corrupt the free space
arena (which also leads to a program crash down the line). I've
never seen an implementation where it would corrupt the stack,
or where it could effectively be used to breech security,
however.

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