XLib Window Name Problems

since 4 days, I try to see how XLib works, and I have finally understood that. Si I tried to make a short program wich retrieve open window's name. For that, I created 2 functions :

Window *list (Display *disp, unsigned long *len) {
    Atom prop = XInternAtom(disp,"_NET_CLIENT_LIST",False), type;
    int form;
    unsigned long remain;
    unsigned char *list;

    if (XGetWindowProperty(disp,XDefaultRootWindow(disp),prop,0,1024,False,XA_WINDOW,
                &type,&form,len,&remain,&list) != Success) {
        return 0;
    }

    return (Window*)list;
}

So, this first function return a window object of all the windows. Then, I created a function to retrieve the name from all those windows.

char *name (Display *disp, Window win) {
    Atom prop = XInternAtom(disp,"WM_NAME",False), type;
    int form;
    unsigned long remain, len;
    unsigned char *list;


    if (XGetWindowProperty(disp,win,prop,0,1024,False,XA_STRING,
                &type,&form,&len,&remain,&list) != Success) {

        return NULL;
    }

    return (char*)list;
}

And this function works fine, an main.c example:

int main(int argc, char* argv[]){
    int i;
    unsigned long len;
    XKeyEvent esend;
    Display *disp = XOpenDisplay(NULL);
    Window *list;
    char *name;

        list = (Window*)list(disp,&len);
    for (i=0;i<(int)len;i++) {
        name = name(disp,list[i]);
        printf("%d :  %s \n",i,name);
        free(name);
        }
}

And, It works really fine, except for Skype windows it returns:

1 : Xlib Programming Manual: Keyboard and Pointer Events - Google Chrome

2 : Debian Web [En fonction] - Oracle VM VirtualBox

3 : XChat: necromoine @ / (+CSTfnst 10:2)

4 :

5 : root@root-Laptop: ~

6 :

And, the number 4 and 6 are blank (I actually have two opened skype window).

Can you help me please.

A WM_NAME is not necessarily a simple string. It could be a compound text (a different type of string), which is actually the case for Skype windows. You need to use AnyPropertyType instead of XA_STRING to get the property, then format according to actual type. Look at the source of xprops to see how it's done.