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Editorial Team
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Asked: 2026-06-12T05:23:20+00:00

I’ve been having this problem for while now, but always seem to put off

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I’ve been having this problem for while now, but always seem to put off asking this question because it seems like I am doing something wrong… but right now I feel otherwise… taken this code:

#include <string>
#include <iostream>
#include <algorithm>
int main(int argc, char** argv)
{
  if(argc < 2)
  {
    std::cout << "usage: " << argv[0] << " <string>" << std::endl;
    return 1;
  }
  std::string str = argv[1];
  std::reverse(str.begin(), str.end());
  std::cout << str << std::endl;
  return 0;
}

Compiled with the command:

g++ -std=c++11 -Wall main.cpp -o main -O0 -ggdb3

I am using a very recent trunk version of gcc, I the trunk was taken around September 23rd ish… Also note that I am not compiling with optimization!

Now anyway, I start debugging, like this:

gdb --quiet --args ./main string

I set a break point at line 12 (the reverse algorithm)

b 12

then I run the program

run

then I try to print out the string, to see what it is

print str

And this, my dear friends, is what seems strange to me:
The output of that previous command is:

No symbol "str" in current context.

a quick check to the local variables doesn’t show the string either

info locals

all I get is

std::__ioinit = {static _S_refcount = 2, static _S_synced_with_stdio = true}

so I’m wondering, am I at fault, or is the compiler or debugger at fault… this has been a pretty pain in the ass problem for a long time for me… so thanks for even reading this question… 🙂

EDIT: now that it has become clear that there is something wrong with my gcc build, I’m wondering if anyone has come across a bug report or any other case where there seems to a be a problem similar to this… I will also try checking with a recent build of gdb to make sure that there is definitely not a problem with my current debugger (that comes with ubuntu)… does that make sense?

EDIT2: So after compiling gdb v7.5, I got relatively the same result except there were no locals present at all… I guess that means it’s a gcc issue, thanks everyone…

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1 Answer

  1. Editorial Team

    No, even with –quiet it works for me. Maybe there’s something wrong with your setup.

    ~/tmp $ g++ -Wall tmp.cpp -o tmp -O0 -ggdb3
~/tmp $ gdb --quiet --args ./tmp string
Reading symbols from /xxxxxxxx/tmp...done.
(gdb) b 12
Breakpoint 1 at 0x400c95: file tmp.cpp, line 12.
(gdb) run
Starting program: /xxxxxxxx/tmp string
Breakpoint 1, main (argc=2, argv=0x7fffffffdc58) at tmp.cpp:12
12        std::reverse(str.begin(), str.end());
(gdb) print str
$1 = "string"
(gdb) info locals
str = "string"
(gdb)
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