How to store a struct or multiple variables inside a Glist object in C

Question

I want to achieve having a linked list in which every link stores 2 integer values. I wanted to achieve this by putting a nested struct inside the glist link. But I get an error which states that my struct is an incompatible data type. What should I do now? I wrote the following Program:

       #include <glib.h>
        
/*  this is the documentation of the glist struct:
struct GList {
  gpointer data;
  GList* next;
  GList* prev;
}
*/
        typedef struct client_data {
            int int1;
            int int2;
        };
        int main(){
    
    //initialize glist
        GList *client_datalist = NULL;
    
    //Data storage which should be temporary because I want to store the data inside the list
        struct client_data tempstruct;
            tempstruct.int1 = 1;
            tempstruct.int2 = 100;
        
            g_list_append (client_datalist, tempstruct);
}

I would appreciate any help with this. I would think there could be a possibility to add 2 integers into the glist link directly but I don't know how I should do that.

Err..., IMHO the correct idiom is client_datalist=g_list_append (client_datalist, tempstruct);. If you do not keep the return value of the initial call on g_list_append, you will just leak the memory used by the newly created list element. Additionally a GList is not a C++ container: it only stores pointers to objects and the caller is responsable for allocating and freeing the objects. — Serge Ballesta
– Serge Ballesta, Commented Sep 22, 2024 at 16:27
Creating a type-alias is like typedef actual_type alias_name;. You have forgotten the alias_name part, and only defined the structure tag and type. The struct client_data { ... } is the actual_type part in your code. That should give build errors. — Some programmer dude
– Some programmer dude, Commented Sep 22, 2024 at 16:27
Also, once you have defined a type-alias, it works like any other type (like for example int). You could do e.g. typedef struct foo { /* some members... */ } bar; and use bar as the type: bar my_foo_structure; — Some programmer dude
– Some programmer dude, Commented Sep 22, 2024 at 16:30

Shelton Liu · Accepted Answer · 2024-09-24 08:24:48Z

2

What you can try to pass a pointer to the data to be stored in the list

GList *client_datalist = NULL;

struct client_data *tempstruct = (struct client_data *)malloc(sizeof(struct client_data));
tempstruct->int1 = 1;
tempstruct->int2 = 100;

g_list_append (client_datalist, tempstruct);

answered Sep 24, 2024 at 8:24

Shelton Liu

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