title: unable to connect callback function fron glade in gtk3 c program
body: <p>I am using learning GTK+ and glade.I want make a program in which when user presses minus button the label number will decrease and if he/she/it presses add button then label number should increase</p>
  
  <p>here is my main.c file:-</p>
  
  <pre><code>#include &lt;gtk/gtk.h&gt;
  
  long a;
  char s[20];
  
  void add(short u)
  {
      ++a;
      sprintf(s,"%ld",a);
  }
  
  void minus(short u)
  {
      --a;
      sprintf(s,"%ld",a);
  }
  
  int main (int arg , char *argv[])
  {
      gtk_init(&amp;arg,&amp;argv);
  
      GtkBuilder *builder = gtk_builder_new();
      gtk_builder_add_from_file(builder,"window1.glade",0);
  
      GtkWidget *win,*num;
  
      win = GTK_WIDGET(gtk_builder_get_object(builder,"window1"));
      num = GTK_WIDGET(gtk_builder_get_object(builder,"label1"));
  
      gtk_builder_connect_signals(builder,0);
      gtk_label_set_text(GTK_LABEL(num),s);
  
      gtk_widget_show_all(win);
  
      gtk_main();
  }
  </code></pre>
  
  <p>Whenever I ran this program I get following in termainal:-</p>
  
  <p>$</p>
  
  <pre><code> ./a.out 
  
  (a.out:3796): Gtk-WARNING **: Could not find signal handler 'minus'.  Did you compile with -rdynamic?
  
  (a.out:3796): Gtk-WARNING **: Could not find signal handler 'add'.  Did you compile with -rdynamic?
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/nBVRC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/nBVRC.png" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/61Fe6.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/61Fe6.png" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/EkY8B.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EkY8B.png" alt="enter image description here"></a></p>
  
  <p>As a complete noob O have no idea what to do next</p>