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Re: Ways to avoid global variables

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On 4/5/20 8:19 PM, James Kuyper wrote:
> On 4/5/20 10:48 AM, James Kuyper wrote:
>> On 4/5/20 4:40 AM, Mehdi Amini wrote:
>>> Hi,
>>>
>>> What are the ways to avoid global variables in C  ;
>>
>> The single most important way is to pass around pointers to those
>> variables, usually as function arguments. Functionally related variables
>> can be grouped into structs, and then you only need to pass around a
>> pointer to a single struct in order to access many different variables.
> 
> I just realized that I left out an important part of that advice. Before
> you pass around those pointers, you should first change the global
> variables to not be global. At worst, they should have file scope
> definitions with internal linkage, but if you can, make them local to a
> function.
> 

Is this an acceptable demo ?

// Code:
#include <stdio.h>
#include <stdlib.h>

#define N 3

typedef struct
{
     int i;
     char c;
} s_t;

s_t * container(s_t *);
s_t * adder(s_t *);
s_t init(void);

s_t caller(void);

int main(void)
{
     s_t ms;
     ms=caller();
     printf("i is %d , c is '%c'\n",ms.i,ms.c);

     return EXIT_SUCCESS;
}

s_t caller(void)
{
     s_t sf=init();
     int ind;
     for(ind=0; ind<N; ind++)
         adder(&sf);
     return sf;
}

s_t * container(s_t * ins)
{
     static s_t cs;
     cs.i=ins->i;
     cs.c=ins->c;

     return &cs;
}

s_t * adder(s_t * ins)
{
     ins->i++;
     ins->c++;

     return ins;
}

s_t init(void)
{
     s_t fs={.i=0 , .c='0'};
     return fs;
}

// Result:
$gcc -o main *.c -Wall -Wextra -pedantic -std=c11
$main
i is 3 , c is '3'


-- 
www.my-c-codes.com/

Farewell.

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Thread

Ways to avoid global variables Mehdi Amini <atorrses@gmail.com> - 2020-04-05 13:10 +0430
  Re: Ways to avoid global variables Mehdi Amini <atorrses@gmail.com> - 2020-04-05 13:23 +0430
  Re: Ways to avoid global variables felix@palmen-it.de (Felix Palmen) - 2020-04-05 11:11 +0200
  Re: Ways to avoid global variables Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-05 02:34 -0700
  Re: Ways to avoid global variables James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-05 10:48 -0400
    Re: Ways to avoid global variables James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-05 11:43 -0400
      Re: Ways to avoid global variables James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-05 16:49 -0400
      Re: Ways to avoid global variables Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2020-04-05 16:12 -0700
    Re: Ways to avoid global variables James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-05 11:49 -0400
      Re: Ways to avoid global variables Mehdi Amini <atorrses@gmail.com> - 2020-04-06 14:11 +0430
        Re: Ways to avoid global variables Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-06 12:08 +0100
  Re: Ways to avoid global variables David Brown <david.brown@hesbynett.no> - 2020-04-05 22:03 +0200
    Re: Ways to avoid global variables James Kuyper <jameskuyper@alumni.caltech.edu> - 2020-04-05 16:53 -0400
      Re: Ways to avoid global variables Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-05 14:11 -0700
      Ice cream (Was: Ways to avoid global variables) gazelle@shell.xmission.com (Kenny McCormack) - 2020-04-06 06:45 +0000
      Re: Ways to avoid global variables David Brown <david.brown@hesbynett.no> - 2020-04-06 09:19 +0200
    Re: Ways to avoid global variables Mehdi Amini <atorrses@gmail.com> - 2020-04-06 13:30 +0430
      Re: Ways to avoid global variables Spiros Bousbouras <spibou@gmail.com> - 2020-04-06 09:25 +0000
        Re: Ways to avoid global variables Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-06 03:03 -0700
          Re: Ways to avoid global variables Spiros Bousbouras <spibou@gmail.com> - 2020-04-06 10:16 +0000
            Re: Ways to avoid global variables Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2020-04-06 03:21 -0700
              Re: Ways to avoid global variables Spiros Bousbouras <spibou@gmail.com> - 2020-04-06 10:50 +0000
              Re: Ways to avoid global variables David Brown <david.brown@hesbynett.no> - 2020-04-06 13:46 +0200
  Re: Ways to avoid global variables scott@slp53.sl.home (Scott Lurndal) - 2020-04-06 18:05 +0000
    Re: Ways to avoid global variables Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-04-06 20:37 +0100

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