How do I share a global variable between c files?

Question

If i define a global variable in a .c file, how can i use the value of the same variable in another .c file?

file1.c

#incl         


        

Answer 1

Use the extern keyword to declare the variable in the other .c file. E.g.:

extern int counter;

means that the actual storage is located in another file. It can be used for both variables and function prototypes.

Answer 2

Do same as you did in file1.c In file2.c:

#include <stdio.h> 

extern int i;  /*This declare that i is an int variable which is defined in some other file*/

int main(void)
{
/* your code*/

If you use int i; in file2.c under main() then i will be treated as local auto variable not the same as defined in file1.c

Answer 3

Use extern keyword in another .c file.

Answer 4

file 1:

int x = 50;

file 2:

extern int x;

printf("%d", x);

Answer 5

If you want to use global variable i of file1.c in file2.c, then below are the points to remember:

1. main function shouldn't be there in file2.c
2. now global variable i can be shared with file2.c by two ways:
   a) by declaring with extern keyword in file2.c i.e extern int i;
   b) by defining the variable i in a header file and including that header file in file2.c.

Answer 6

using extern <variable type> <variable name> in a header or another C file.