What is the alternative for extern in C language?

Question

What coding methodology could be the best alternative for extern

Answer 1

An extern variable is a declaration (thanks to sbi for the correction) of a variable which is defined in another translation unit. That means the storage for the variable is allocated in another file.

Say you have two .c-files test1.c and test2.c. If you define a global variable int test1_var; in test1.c and you'd like to access this variable in test2.c you have to use extern int test1_var; in test2.c.

Complete sample:

$ cat test1.c
int test1_var = 5;
$ cat test2.c
#include <stdio.h>
extern int test1_var;
int main(void)
{
printf("test1_var = %d\n", test1_var);
return 0;
}
$ gcc test1.c test2.c -o test
$ ./test test1_var = 5

Answer 2

I am just asking for an alternative coding methodology for extern