const char* access: ld returned 1 exit status

Question

I have a header file config.h where I'm simply defining a string with a value using

namespace configuration {
    const char* name = "test";
}

And I access it from a .cpp file as configuration::name. But then I'm getting a compiler error:

error: ld returned 1 exit status

If I change it to const string name = "test"; it works. Why? And how do I fix this to be able to use a const char* instead?

How are you accessing it in your `cpp` file? You might be trying to assign `const char*` to something that doesn't work with it whereas using `string` works. — user2205930, Oct 05 '17 at 20:34
I just included config.h and accessed it via configuration::name There are no other errors. That is all that was given. — Pah Zon, Oct 05 '17 at 20:43
Found a solution, fixed by changing it to: const char *const but can someone explain why this works? — Pah Zon, Oct 05 '17 at 20:48
@PahZon: Two lines above the `error: ld...` line, do you not see something like: `/tmp/cc6c2o6v.o:(.data+0x0): multiple definition of `configuration::name'`? — rici, Oct 05 '17 at 22:02

score 1 · Answer 1 · answered Oct 05 '17 at 21:05

The difference between the two strings

namespace config {
  const char* test1 = "test1";
  const std::string test2 = "test2";
}

is that the second is const and hence has internal linkage, while the first is not (it's merely a pointer to a const) and requires external linkage, i.e. you must provide a definition in some .cpp file, failing of which causes your linker error.

const char* access: ld returned 1 exit status

1 Answers1