const vs #define

[Jose Luis]

Hi,

Given the code below:


<<<snip begin>>>

m3vmsa3.rraaupma /tmp > more p1.c p2.c defs.h

#include "defs.h"

int main()
{}

....skipping...

#include "defs.h"
....skipping...
#ifndef DEFS_H
#define DEFS_H

const char* STR1="Hello World";
const int i1=0;

#endif

<<<snip end>>>


If compiled:

m3vmsa3.rraaupma /tmp > aCC p1.c p2.c
p1.c:
p2.c:
/usr/ccs/bin/ld: Duplicate symbol "STR1" in files p1.o and p2.o
/usr/ccs/bin/ld: Found 1 duplicate symbol(s)


What is the best option for STR1: "static const" or "#define"?

Why is "i1" not a duplicate symbol?



Thanks in advance,
Jose Luis.

 

[James Kanze]

i1 is a const (by itself). STR1 is not a const, it's a
regular pointer to a const char. Make it

const char* const STR1 = ...

and it will be const.

Alternatively, he could just skip the pointer:

char const STR1[] = "Hello World" ;

Most of the time, this is probably closer to what is actually
wanted.