GTK Entry to Integer conversion - c++

Question

How do you get the text from a gtk entry widget and then convert that to an integer value. Notice in my code I include a wrapper struct called Window that contains pointers to widgets. In the main, I declare an instance of a Window and then build the correct widgets with the appropriate GTK function calls. I then pass that window object to the function that handles the clicked action. I want to then calculate the numerator divided by the denominator in integer format. Below is my attempt. All the code works except for the button_clicked function. Any ideas?
#include <gtk/gtk.h>
#include <stdlib.h>
struct Window
{
GtkWidget *numerator;
GtkWidget *denominator;
GtkWidget *button;
GtkWidget *label;
};
void button_clicked(GtkWidget *widget, gpointer data)
{
Window* w = (Window*)data;
char buf[10];
char buffer[200];
GtkEntry* e = (GtkEntry*)w->numerator;
const gchar* entry1 = gtk_entry_get_text(e);
char* test = (char*)gchar;
int r = atoi(test);
sprintf(buf,"%d",r);
GtkWidget *label = w->label;
gtk_label_set_text(GTK_LABEL(label), buf);
}
int main(int argc, char*argv[])
{
GtkWidget *window;
GtkWidget *table;
Window w;
//Set up my window
gtk_init(&argc,&argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_title(GTK_WINDOW(window), "Division");
gtk_window_set_default_size(GTK_WINDOW(window),500,500);
gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
//Create my table and add it to the window
table = gtk_table_new(4,2,FALSE);
gtk_container_add(GTK_CONTAINER(window),table);
//Create instances of all my widgets
w.numerator = gtk_entry_new();
w.denominator = gtk_entry_new();
w.button = gtk_button_new_with_label("Click");
w.label = gtk_label_new("result");
//Attack the widgets to the table
gtk_table_attach(GTK_TABLE(table), w.numerator,0,1,0,1,GTK_FILL,GTK_FILL,5,5);
gtk_table_attach(GTK_TABLE(table), w.denominator,0,1,1,2,GTK_FILL,GTK_FILL,5,5);
gtk_table_attach(GTK_TABLE(table), w.button,0,1,2,3,GTK_FILL,GTK_FILL,5,5);
gtk_table_attach(GTK_TABLE(table), w.label,0,1,3,4,GTK_FILL,GTK_FILL,5,5);
//attach the click action to with the button to invoke the button_clicked function
g_signal_connect(G_OBJECT(w.button),"clicked",G_CALLBACK(button_clicked),&w);
g_signal_connect_swapped(G_OBJECT(window),"destroy",G_CALLBACK(gtk_main_quit),NULL);
gtk_widget_show_all(window);
gtk_main();
return 0;
}

Answer 1

If I see this correctly, in your "test code" all you're trying to do is set the label string to the contents of "w->numerator", right?
The line
char* test = (char*)gchar;
looks fishy to me and doesn't even compile, it looks like a typo.
Change the "gchar" to "entry1", and it should do what you want it to.
I have a recommendation for you though: use GtkSpinButton instead of GtkEntry. It is like a custom Entry made for numerical values, and the retrieval of such is many times easier.