############## External File to Import with Original Variable (var) Definition #########

filename: my_variable.c

int var = 22;

################ Calling Main Function ####################3

filename: main.c

#include

/* After importing the external variables file Compilation will work*/

#include "my_variable.c"

/**

* Extern keyword means that

* during linking the compiler will scan through

* all other c-file and locate a defined variable

* "int var = "

* and incorporated to this main function

*/

extern int var;

int main(int argc, char **argv, char **envp)

{

printf("Original value is %d\n",var);

var = 10;

printf("Updated value is %d\n",var);

return (0);

}

/* Compiling this program will fail because the var variable is not defined

* anywhere in the program*/

/**

######## Compiling the Program #############333

$ gcc main.c -o a.out

$ ./a.out

# program Output #

Original value is 22

Updated value is 10