Thread: Structures problem

Writing a weather program and I'm using a structure to keep the current weather data. Right now I have two source files - main.c and rssparse.c. rssparse contains all the functions I need to read the data.

I have the "current" structure defined in main.c as...

Code:

.....<insert includes and other stuff here>
struct weatherdata{
   int temp;
   char *status;
   int humidity;
   int windspeed;
   char winddirection;
   float barometer;
   int dewpoint;
   int heatindex;
   int windchill;
   int visibility;
} current; 

int main(void){
<....program goes here>

Then in rssparse.c I'm trying to access that in a function via -

Code:

      if (!strcmp(idname, "humidity")) current.humidity = atoi(value);
      else if (!strcmp(idname, "windspeed")) current.windspeed = atoi(value);
      else if (!strcmp(idname, "dewpoint")) current.dewpoint = atoi(value);
      else if (!strcmp(idname, "heatindex")) current.heatindex = atoi(value);
      else if (!strcmp(idname, "windchill")) current.windchill = atoi(value);
      else if (!strcmp(idname, "visibility")) current.visibility = atoi(value);

Compile and...

In file included from main.c:30:
rssparse.c: In function `ParseHTML':
rssparse.c:160: error: `current' undeclared (first use in this function)
rssparse.c:160: error: (Each undeclared identifier is reported only once
rssparse.c:160: error: for each function it appears in.)
main.c: At top level:
main.c:50: error: `current' used prior to declaration

I've tried declaring the structure in rssparse in every way I can think of. extern struct current, extern current, etc. All I want to do is access the bloody structure globally!

So do any of you C gods know what I'm doing wrong?

in rssparse.c:

Code:

extern struct weatherdata{
   int temp;
   char *status;
   int humidity;
   int windspeed;
   char winddirection;
   float barometer;
   int dewpoint;
   int heatindex;
   int windchill;
   int visibility;
} current;

Done and:

main.c:39: error: redefinition of `struct weatherdata'
jlpence@linux:~/weather>

At least I'm down to one error.

Post main.c, at least any references to struct weatherdata

The top of the code for both programs:

main.c

Code:

#define TRUE 1
#define FALSE 0
#define DEBUG 1      // Verbose output, handy for development
#define SUPERDEBUG 0 // VERY verbose output! Annoying but helpful.

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "rssparse.c"

extern int ProcessRSSFeed(char *filename);
int FileExists(char *filename);
int GetFileSize(char *filename);
void DebugMsg (char *message, char *info);
void Fatal (char *message, char *info);
void SDebugMsg (char *message, char *info);

struct weatherdata{
   int temp;
   char *status;
   int humidity;
   int windspeed;
   char winddirection;
   float barometer;
   int dewpoint;
   int heatindex;
   int windchill;
   int visibility;
} current; 


int main(void){
.....Code goes here

rssparse.c

Code:

static int ClosingTag(char *buffer, char *tag);
int ProcessRSSFeed(char *filename);
static void Cut (char *begin, char *end);
static void ParseBracketTag(char *buffer);
static void ParseHTML(char *buffer);
static void ParseXML(char *buffer);

extern int FileExists(char *filename);
extern int GetFileSize(char *filename);
extern void DebugMsg (char *message, char *info);
extern void Fatal (char *string, char *buffer);
extern void SDebugMsg (char *message, char *info);

extern struct weatherdata current; 


static int ClosingTag(char *buffer, char *tag){
.....more code goes here

Note that I did try quzah's advice (included in above code, in fact), and got the following:

rssparse.c: In function `ParseHTML':
rssparse.c:161: error: invalid use of undefined type `struct weatherdata'
rssparse.c:162: error: invalid use of undefined type `struct weatherdata'
rssparse.c:163: error: invalid use of undefined type `struct weatherdata'
rssparse.c:164: error: invalid use of undefined type `struct weatherdata'
rssparse.c:165: error: invalid use of undefined type `struct weatherdata'
rssparse.c:166: error: invalid use of undefined type `struct weatherdata'
jlpence@linux:~/weather>

Accessing the structures via the exact code listed in my first post.

You need to use a header file.

Code:

#include "rssparse.c"

It is not a good idea to include one c file in another. You need to create a header file.

Sample rssparse.h:

Code:

/* Declare the structure so that every file can use it */
struct weatherdata{
   int temp;
   char *status;
   int humidity;
   int windspeed;
   char winddirection;
   float barometer;
   int dewpoint;
   int heatindex;
   int windchill;
   int visibility;
}; 

/* Declare an instance of the structure. It is labelled extern
 * so that each file knows the instance exists but space is 
 * not reserved. */
extern struct weatherdata current;

#include this header in every C file where you want to use the "weatherdata" structure or the instance "current".

Now, in one c file only, you have to declare the instance.

Code:

struct weatherdata current

This reserves space for "current". Each other file where "current" is used is told to link to this space by the extern declaration.

Dear anonytmouse,

After two days of mucking with this it finally works. I would like to buy you beer.

Love,
me.