GTK3 :How to receive input value from entry/input box? - c++

Question

I am pretty new to GTK and I want to know how to resize the entry boxes size and and the spacing between label and boxes ?
Also, how to receive the input value from the entry box for further usage you know, like the C function "scanf". Thanks you and sorry for my bad English
#include <stdio.h>
#include <stdlib.h>
#include <gtk/gtk.h>
static void destroy(GtkWidget *widget, gpointer data){
gtk_main_quit ();
}
static void initialize_window(GtkWidget* window) {
gtk_window_set_title(GTK_WINDOW(window),"My Window");
gtk_window_set_default_size (GTK_WINDOW (window), 200, 100);
g_signal_connect (window, "destroy", G_CALLBACK (destroy), NULL);
}
int main (int argc, char *argv[]){
GtkWidget *window,*table,*label,*entry, *entry1, *label1, *label3, *label2, *entry2;
gtk_init(&argc, &argv);
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
initialize_window(window);
table = gtk_table_new(4, 2, TRUE);
gtk_container_add (GTK_CONTAINER (window), table);
label = gtk_label_new ("Circle with standard formula:(x-a)^2 + (y-b)^2 =r*r");
gtk_misc_set_alignment (GTK_MISC (label), 70, 70);
gtk_table_set_homogeneous(GTK_TABLE (table), TRUE);
gtk_table_attach_defaults (GTK_TABLE (table), label, 0, 1, 0, 1);
entry = gtk_entry_new ();
gtk_table_attach_defaults (GTK_TABLE (table), entry, 1, 2, 1, 2);
label1 = gtk_label_new ("Input value of a:");
gtk_table_set_homogeneous(GTK_TABLE (table), TRUE);
gtk_table_attach_defaults(GTK_TABLE (table), label1, 0, 1, 1, 2);
entry1 = gtk_entry_new();
gtk_table_attach_defaults(GTK_TABLE(table), entry1, 1, 2, 2, 3);
label2=gtk_label_new("Input the value of b:");
gtk_table_set_homogeneous(GTK_TABLE(table), TRUE);
gtk_table_attach_defaults(GTK_TABLE (table), label2, 0, 1, 2, 3);
label3=gtk_label_new("Input the value of r:");
gtk_table_set_homogeneous(GTK_TABLE(table), TRUE);
gtk_table_attach_defaults(GTK_TABLE (table), label3, 0, 1, 3, 4);
entry2 = gtk_entry_new();
gtk_table_attach_defaults(GTK_TABLE(table), entry2, 1, 2, 3, 4);
gtk_widget_show_all(window);
gtk_main ();
return 0;
}

Answer 1

In order to get the text within one of your entry boxes use the gtk_entry_get_text function found in more detail here: https://developer.gnome.org/gtk3/stable/GtkEntry.html#gtk-entry-get-text
For instance:
buffer = gtk_entry_get_text(&entry1);
As far as changing spacing between elements goes the Gtk documentation notes that if you do not need individual row spacing then GtkGrid is preferred as it appears many of the table functions are deprecated since Gtk 3.4.
To set the spacing between rows use gtk_table_set_row_spacing found here: https://developer.gnome.org/gtk3/stable/GtkTable.html#gtk-table-set-row-spacing
and just below that is listed the information on gtk_table_set_col_spacing.
Setting the padding within table cells is a bit different and would be controlled using x-padding and y-padding properties of the child elements, more information on this is listed at the bottom of the GtkTable page.