On Tue, Jul 01, 2014 at 01:39:03AM -0700, Anoop Neem wrote:
This application is intended to convert value entered in Text entry
field (in Celcius) to Farenheit in label. I was having hard time in
altering the properties of two widgets (other than calling widget) in
the same callback, hence created a structure 'struct mulptr' for passing
two widgets. But when i click on the button application closes giving me
some error:
xxx@ubuntu:~/gtk$ gcc `pkg-config --cflags gtk+-3.0` -o 4 4.c
`pkg-config --libs gtk+-3.0`
xxx@ubuntu:~/gtk$ ./4
(4:4221): Gtk-CRITICAL **: gtk_entry_get_text: assertion 'GTK_IS_ENTRY
(entry)' failed
Segmentation fault (core dumped)
This basically means that the pointer that you passed to
gtk_entry_get_text was not pointing to a GtkEntry.
-
#includegtk/gtk.h
#includestring.h
#includestdlib.h
char a[15] = Result here;
struct mulptr
{
GtkWidget *one;
GtkWidget *two;
};
int tofarenheit(int c)
{
return (c*1.8 + 32);
}
void calculate(GtkWidget *widget, gpointer data)
{
GtkWidget *textEntry = ((struct mulptr *)data)-one;
GtkWidget *label = ((struct mulptr *)data)-two;
int res = 0, F;
res = atoi(gtk_entry_get_text(GTK_ENTRY(textEntry)));
if(res)
{
F = tofarenheit(res);
sprintf(a, %d, F);
}
else
strcpy(a, Invalid Input!);
gtk_label_set_text(GTK_LABEL(label), a);
}
int main(int argc, char *argv[])
{
//Decleration
GtkWidget *window;
GtkWidget *calButton;
GtkWidget *textEntry;
GtkWidget *label;
GtkWidget *grid;
struct mulptr *p = (struct mulptr *)malloc(sizeof(struct mulptr));
p-one = textEntry;
At this point textEntry is still not initialized, so all this did was
copy the uninitialized value from textEntry to p-one.
p-two = label;
//Initilization
gtk_init(argc, argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
//gtk_window_set_default_size(GTK_WINDOW(window), 480, 320);
gtk_window_set_title(GTK_WINDOW(window), Celcius to Ferenheit
Converter);
gtk_container_set_border_width(GTK_CONTAINER(window), 10);
grid = gtk_grid_new();
label = gtk_label_new(a);
textEntry = gtk_entry_new();
And here you assign textEntry with the pointer to your new GtkEntry, but
p-one is not updated and sill contains the old value which is used in
calculate.
calButton = gtk_button_new_with_label(Calculate);
//Adding widget to frame
gtk_container_add(GTK_CONTAINER(window), grid);
gtk_grid_attach(GTK_GRID(grid), textEntry, 0, 0, 1, 1);
gtk_grid_attach(GTK_GRID(grid), label, 1, 0, 1, 1);
gtk_grid_attach(GTK_GRID(grid), calButton, 0, 1, 1, 1);
//Signal Handlers
g_signal_connect (window, delete-event, G_CALLBACK (gtk_main_quit),
NULL);
g_signal_connect (calButton, clicked, G_CALLBACK(calculate), p);
//Essentials
gtk_widget_show_all(window);
gtk_main();
return 0;
}
-
Please help me with this piece of code?? Is it all right to use this
kind of struct??
In a large application sure, it makes sense to bundle related things
together as a struct and passit around; but that's not really necessary
in a small application like this. Since you're using Gtk you might just
as well want to check out GObject which formalizes a lot of this stuff.
Marcus
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