global hashmap can't be seen outside of where it's declared about hashmap

[DavidLeeds]

Hi @lpipes,

Can you provide a snippet of code with your desired usage? I might be able to identify an issue. There should be no problems using this library how you have described.

As always, I would highly recommend compiling C code with -Wall and -Werror compiler options so the compiler identifies obvious issues.

[lpipes]

Thank you! It's probably something I don't understand. I tried to make this MWE but now it won't compile. I tried to compile with gcc -g -pg -w -o main main.c findABC.c hashmap.c

global.h:

#include "hashmap.h"
#include "hashmap_base.h"

typedef struct leafMap{
	char* name;
	int root;
	int node;
}leafMap;
extern struct hashmap_base map;

main.c:

#include <stdbool.h>
#include <stdint.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "hashmap.h"
#include "hashmap_base.h"
#include "global.h"

struct hashmap_base map;

int main()
{
        HASHMAP(char, struct leafMap) map;
	hashmap_init(&map,hashmap_hash_string, strcmp);
	struct leafMap *l;
	l = malloc(sizeof(leafMap));
	l->name=malloc(10*sizeof(char));
	strcpy(l->name,"ABC");
	l->root=12;
	l->node=5;
	hashmap_put(&map,l->name,l);
	findABC();
	free(l->name);
	free(l);
}

and findABC.c:

#include <stdbool.h>
#include <stdint.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "hashmap.h"
#include "hashmap_base.h"
#include "global.h"

void findABC(){
	struct leafMap *l;
	l=hashmap_get(&map,"ABC");
	printf("Key: %s, Root: %d, Node: %d\n", l->name, l->root, l->node);
}

[lpipes]

I'm able to compile and run this code correctly but not the previous code. I compiled with gcc -g -pg -w -o main main.c hashmap.c

global.h:

#include "hashmap.h"
#include "hashmap_base.h"

typedef struct leafMap{
	char* name;
	int root;
	int node;
}leafMap;

main.c:

#include <stdbool.h>
#include <stdint.h>
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "hashmap.h"
#include "hashmap_base.h"
#include "global.h"

HASHMAP(char, struct leafMap) map;

void findABC(){
	struct leafMap *l;
	l=hashmap_get(&map,"ABC");
	printf("Key: %s, Root: %d, Node: %d\n", l->name, l->root, l->node);
}
int main()
{
        hashmap_init(&map,hashmap_hash_string, strcmp);
	struct leafMap *l;
	l = malloc(sizeof(leafMap));
	l->name=malloc(10*sizeof(char));
	strcpy(l->name,"ABC");
	l->root=12;
	l->node=5;
	hashmap_put(&map,l->name,l);
	findABC();
	free(l->name);
	free(l);
}

./main 
Key: ABC, Root: 12, Node: 5

[fancong5201314]

Your application scenario is the same as mine. I use global variables and use locking. I also have similar problems. I once suspected that it was my own use problem.

[fancong5201314]

I use this to replace the redundant map table of C++. Now hashmap supports adding, deleting, and querying, but it has not been modified.

[DavidLeeds]

A few notes:

1. In the original code, the FindABC() declaration was not visible to main.c. The second (working) version moved the function to main.c where it was visible.
2. There is no need to include hashmap_base.h. Just include hashmap.h.
3. Don't forget to call hashmap_cleanup() to free memory used by the data structure when you're done using it.