在头文件中设置常量char *？

Question

If I wanted to set a private, constant character array in a header file, how could you do that? Compilers don't seem to like it.. Here is what I tried.

static const char *foo = "SomeCharArray";

Answer 1

Use extern keyword in the following way.

// myfile.h
extern const char* foo;

// myfile.cpp
const char* foo = "SomeCharArray";

Answer 2

The following code compiles fine:

consty.h:

static const char *foo = "SomeCharArray";

consty.c:

#include <stdio.h>
#include "consty.h"
int main()
{
    printf ("Hi %s\n", foo);
    return 0;
}

Note that any file that includes consty.h will get its own copy of foo. Other people have described the proper way to share global variables with extern .

Answer 3

file.h:

extern const char* foo;
#define FOO_DATA "SomeCharDATA"

file.c:

const char *foo = FOO_DATA;

Answer 4

Given that this:

static const char *foo = "SomeCharArray";

is a perfectly valid C (even in an header file) I think you should ask yourself why you want this in an header!

If you need a variable scope to be restricted to a .c file just put the declaration in that file. If you find yourself in need of sharing private data between two .c files, you probably have not split the functions and data in the most appropriate way across your files.