gdb reports wrong values in simple program. Why?

Question

#include <iostream>
int main ()
{
  int* a = new int[15];
  a[0] = 42;
  a[1] = 43;
  std::cerr << a[0];

  return 0;
}

gdb says a = 0xffffffff and 'print a[0]' gives 'cannot access memory address' but why? If run outside of gdb, the program prints out '42' as expected. What is going on here? Compiled with 'g++ test2.cpp -gstabs+ -O0 -o test2'.

Are you sure you aren't trying to access a before new is invoked? — rlibby
– rlibby, Commented May 2, 2011 at 21:20

user2100815 · Accepted Answer · 2011-05-02 21:30:45Z

1

Which platform are you are on? The gstabs+ debugger format is not universally supported, if you want to use it you must acquaint yourself with the fascinating differences between COFF, DWARF 2 and probably some other exe/debug formats I've never heard of. Bottom line - read the gdb manual. But your code will almost certainly work correctly if you simply use the -g flag.

answered May 2, 2011 at 21:30

user2100815

Sign up to request clarification or add additional context in comments.

1 Comment

Philip G. Lee Over a year ago

I started using stabs+ years ago when I was having problems with debugging a c++ program. I tried all the formats and stabs+ was the only one that worked correctly at the time. I have stuck with it ever since, and this is the first problem I've had with it.

sehe · Accepted Answer · 2011-05-02 21:26:43Z

0

Yep I can reproduce that, but only with -gstabs+

So: why are you using -gstabs+?

It doesn't sound fair, but it is an honest question, what advantage does stabs+ bring over 'normal' debug info?

answered May 2, 2011 at 21:26

sehe

400k49 gold badges475 silver badges673 bronze badges

Collectives™ on Stack Overflow

gdb reports wrong values in simple program. Why?

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related