I would like to take an array of strings in a macro. Firstly: is that possible?
IF yes, can I call them one by one based on the index, when I am using them?
Something like this:
#define VAR "abc", "def", "xyz"
Then when i want to use "def" somewhere,
FUNC(VAR[1]);
May be my code helpful to you:
#include<stdio.h>
#include<stdlib.h>
#define STRING_ARRAY "ONE", "TWO", "THREE", "NULL"
int main(){
char* STRING[] = {STRING_ARRAY};
int i=0;
scanf("%d",&i);
printf("%s\n",STRING[i]);
return EXIT_SUCCESS;
}
This also works:
:~$ gcc x.c -o x
:~$ ./x
1
TWO
e:~$ ./x
2
THREE
You have to change in MACRO only in at re-compilation.
char* STRING[] = {STRING_ARRAY}; with char* STRING[] = {"ONE", "TWO", "THREE", "NULL"}; before this source file is compiled, which makes that macro a bit useless.define rather than copy-paste it :)#define VAR(...) const char *FOO[] = { __VA_ARGS__ }
...
VAR("abc", "xyz");
printf("%s\n", FOO[0]);
But note:
char const* [] at least. And then as you do it, yes this is evil, one should never do this like that. Provide the name of the variable as an argument.
const char *. Don't know how to be with the name, OP wants just a macro that receives strings as parameters. There can be a misunderstanding, I think.Starting with C99 you can use compound literals
#define VAR ((char const*[]){ "abc", "def", "xyz" })
and then use this as VAR[2] or so.
A compound literal is similar to a cast of an initializer, here this is an array of base type char const*. The const is important such that you don't inadvertently try to modify the string literals.
Any modern compiler should be able to fold all different occurrences of that array and of the string literals into one single instance.
The macro will expand to the text on the right so try to answer your question for yourself.
Here is a way to try to understand macro-s:
FUNC(VAR[1]); <=> FUNC("abc", "def", "xyz"[1]);
Will the one on the right do what you expect? No? So then you can't use it like this. However you can use this for static array initilization and then access the array by index for instance.
EDIT: here is how I propose you to use the MACRO:
char* a[] = {VAR};
FUNC(a[0]);
