How to access C variables in .c files ?

[JaMe]

I have variable called "Timer1" in file "main.c".
The problem is, is there any way to access those variable in other file, e.g, in file "init.c" ?

 

[echo47]

variable in C

Are main.c and init.c compiled into one executable?
If main() calls init(), then the call could pass a pointer to Timer1.

#include <stdio.h>

void init(int *value)
{
  printf(" Value = %d\n", *value);
  *value *= 2;
  printf(" Value = %d\n", *value);
}

int main(void)
{
  int Timer1 = 123;
  printf("Timer1 = %d\n", Timer1);
  init(&Timer1);
  printf("Timer1 = %d\n", Timer1);
  return 0;
}

Output:

Timer1 = 123
 Value = 123
 Value = 246
Timer1 = 246

 

[alzomor]

Re: variable in C

hi

in the file init.c put
extern datatype Timer1;
this is if the variable Timer1 is global variable in file main.c

For more details check the keyword extern.
**broken link removed**


Salam
Hossam Alzomor
www(.)i-g(.)org

 

[funster]

Re: variable in C

you can't access it unless you define the variable outside main function.

I have variable called "Timer1" in file "main.c".
The problem is, is there any way to access those variable in other file, e.g, in file "init.c" ?

 

[waterman]

Re: variable in C

in "init.c"

extern int Timer1;

void init(void)
{
Timer1 = 0;
}

//----------------------------------------
in "main.c"

int Timer1;

extern void init(void);

int main(void)
{
init();

//other codes

return 0;
}

 

[booklog]

Re: variable in C

The variable Timer1 should be global

 

[jhbbunch]

variable in C

U need the extern statement. That plus the function prototype tell the compiler/likerhow to set up the call, what to return from it, what the storage spaces required are and also. extern tells the compiler it will find the function (or a variable) in another file.

 

[inirs06]

variable in C

One way of doing this is to create a main.h, decalre this variable as extern and then include the main.h in the init.c file. This is needed if the compiler enforces ansi stds strictly. Otherwise, make sure that u link both files after compilation, use the extern keyword directly in your init.c file.