C++ using getline() prints: pointer being freed was not allocated in XCode

Question

I'm trying to use std:getline() but getting a strange runtime error:

malloc: * error for object 0x10000a720: pointer being freed was not allocated * set a breakpoint in malloc_error_break to debug

This is the code that produces this error:

//main.cpp
#include <iostream>
#include <sstream>

int main (int argc, char * const argv[])
{
   std::istringstream my_str("demo string with spaces");
   std::string word;

   while (std::getline(my_str, word, ' ')) {
        std::cout << word << std::endl;
   }
   return 0;
}

Before each word I get this error. From the comments it seems to be a OSX/XCode specific error. Any hints on that?

Update: The error is only printed in Debug mode. If I build this code in Release mode everything is fine.

Update 2: More info on that issue can be found here.

Solution:

Set

_GLIBCXX_FULLY_DYNAMIC_STRING=1

in your Preprocessor Macros in targets info build tab.

System info:

OSX 10.6.2 | XCode 3.2 | g++ 4.2 | debug config for i386

Jacey

It runs fine on my machine. I'm not using a MacBook though so that might have something to do with it maybe but on XP with VS2008 it compiles and runs fine. – Trehalose

Likewise, it compiles and runs without errors on my PPC Powerbook. Mac OS 10.4 with g++ 4.0.1. And it looks right... – Cottrill

Compiles and runs fine under Visual Studio 2008 for me too. – Whiplash

Works fine for me on my MacBook Pro with 10.5.8 g++ 4.0.1 and valgrind doesn't report anything suspicious either. – Slant

Works fine for me, MacBook Pro, 10.6.2 and g++ 4.2.1. Where does malloc_error_break get called? – Flite

@Potatoswatter: right before it prints the word. – Jacey

@dan: Looks like your setup may be wonky somehow. Try it with terminal g++ in a fresh terminal, then consider a reboot, then consider a reinstallation of the developer tools. – Cottrill

getline => string::append => string::reserve => free: I can reproduce it only within XCode, not from the command line. – Flite

To reproduce with Xcode, make sure to include -D_GLIBCXX_DEBUG on the g++ command line. – Bordie

Answer 1

At least one person has reported problems with g++ 4.2.1 on Apple that seem possibly related to yours having to do with an improper configuration of the standard library with the _GLIBCXX_FULLY_DYNAMIC_STRING definition (not that I understand any of what I'm typing here).

You might get a bit of a clue from the newsgroup thread that includes this message:

• http://gcc.gnu.org/ml/gcc-bugs/2009-10/msg00807.html

Superfluid

This is it. I reproduced the problem and fixed it by adding _GLIBCXX_FULLY_DYNAMIC_STRING to the target settings window. (Do not add it to the "Preprocessing" section of the Project settings window; that does nothing. XCode, grrrrr…) – Flite

Since this is a team effort, would someone like to report a bug? – Flite