gtk_entry_get_text：断言'GTK_IS_ENTRY (entry)'失败

我正在用C++和GTK3创建一个小程序（只是学习它），但我遇到了麻烦。所以，我孤立了有问题的部分。

它被用来获取条目并在单击按钮时打印它。

这是代码：

#include <iostream>
#include <gtk/gtk.h>
using namespace std;
GtkWidget *wventana;
GtkWidget *wgrid;
//FUNCS
void ventana(string titulo, int margen)
{
    const char * tituloc = titulo.c_str();
    wventana = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_set_position (GTK_WINDOW (wventana), GTK_WIN_POS_CENTER);
    gtk_window_set_title (GTK_WINDOW (wventana), tituloc);
    gtk_container_set_border_width(GTK_CONTAINER(wventana), margen);
}
void grid()
{
    wgrid = gtk_grid_new();
    gtk_container_add(GTK_CONTAINER(wventana), wgrid);
    gtk_grid_set_row_spacing (GTK_GRID (wgrid), 10);
    gtk_grid_set_column_spacing (GTK_GRID (wgrid), 25);
}
void boton_clic (GtkEntry *wentrada, gpointer user_data)
{
    const char *nombre;
    nombre = gtk_entry_get_text(wentrada);
    cout << nombre << endl;
}
void entrada(int x, int y, int lx, int ly)
{
    GtkWidget *wentrada;
    wentrada = gtk_entry_new();
    gtk_grid_attach (GTK_GRID (wgrid), wentrada, x, y, lx, ly);
}
void boton(string texto, int x, int y, int lx, int ly)
{
    const char * wtexto = texto.c_str();
    GtkWidget *wboton;
    wboton = gtk_button_new_with_label (wtexto);
    gtk_grid_attach (GTK_GRID (wgrid), wboton, x, y, lx, ly);
    g_signal_connect (GTK_BUTTON (wboton), "clicked", G_CALLBACK (boton_clic), G_OBJECT     (wventana));
}
//MAIN
int main(int argc, char *argv[])
{
    gtk_init (&argc, &argv);
    ventana("ventana",10);
    grid();
    entrada(1, 1, 1, 1);
    boton("Aprietame", 1, 2, 1, 1);
    gtk_widget_show_all (wventana);
    gtk_main ();
    return 0;
}

它无法获取条目，并显示以下错误消息：

(boton:6669): Gtk-CRITICAL **: gtk_entry_get_text: assertion 'GTK_IS_ENTRY (entry)' failed

有人能告诉我问题出在哪里吗？还有，我该如何让它发挥作用？或者在任何情况下，有什么好的替代方案可以做到这一点？（必须具有独立的功能）

提前谢谢。

谢谢你的回答@potomato，我试着用你提出的更改来替换，是新代码：

#include <iostream>
#include <gtk/gtk.h>
using namespace std;
GtkWidget *wventana;
GtkWidget *wgrid;
//FUNCS
void ventana(string titulo, int margen)
{
    const char * tituloc = titulo.c_str();
    wventana = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_set_position (GTK_WINDOW (wventana), GTK_WIN_POS_CENTER);
    gtk_window_set_title (GTK_WINDOW (wventana), tituloc);
    gtk_container_set_border_width(GTK_CONTAINER(wventana), margen);
}
void grid()
{
    wgrid = gtk_grid_new();
    gtk_container_add(GTK_CONTAINER(wventana), wgrid);
    gtk_grid_set_row_spacing (GTK_GRID (wgrid), 10);
    gtk_grid_set_column_spacing (GTK_GRID (wgrid), 25);
}
void boton_clic (GtkButton *wboton, GtkEntry *wentrada)
{
    const char *nombre;
    nombre = gtk_entry_get_text (wentrada);
    cout << nombre << endl;
}
void entrada(int x, int y, int lx, int ly)
{
    GtkWidget *wentrada;
    wentrada = gtk_entry_new();
    gtk_grid_attach (GTK_GRID (wgrid), wentrada, x, y, lx, ly);
}
void boton(string texto, int x, int y, int lx, int ly)
{
    const char * wtexto = texto.c_str();
    GtkWidget *wboton;
    wboton = gtk_button_new_with_label (wtexto);
    gtk_grid_attach (GTK_GRID (wgrid), wboton, x, y, lx, ly);
    g_signal_connect (wboton, "clicked", G_CALLBACK (boton_clic), wentrada);
}
//MAIN
int main(int argc, char *argv[])
{
    gtk_init (&argc, &argv);
    ventana("ventana",10);
    grid();
    entrada(1, 1, 1, 1);
    boton("Aprietame", 1, 2, 1, 1);
    gtk_widget_show_all (wventana);
    gtk_main ();
    return 0;
}

但当我试图编译它时，它显示：

In file included from /usr/include/glib-2.0/gobject/gobject.h:28:0,
                 from /usr/include/glib-2.0/gobject/gbinding.h:29,
                 from /usr/include/glib-2.0/glib-object.h:23,
                 from /usr/include/glib-2.0/gio/gioenums.h:28,
                 from /usr/include/glib-2.0/gio/giotypes.h:28,
                 from /usr/include/glib-2.0/gio/gio.h:26,
                 from /usr/include/gtk-3.0/gdk/gdkapplaunchcontext.h:28,
                 from /usr/include/gtk-3.0/gdk/gdk.h:32,
                 from /usr/include/gtk-3.0/gtk/gtk.h:30,
                 from boton.cpp:2:
boton.cpp: In function ‘void boton(std::string, int, int, int, int)’:
boton.cpp:51:64: error: ‘wentrada’ was not declared in this scope
  g_signal_connect (wboton, "clicked", G_CALLBACK (boton_clic), wentrada);
                                                                ^
/usr/include/glib-2.0/gobject/gsignal.h:472:73: note: in definition of macro     ‘g_signal_connect’
     g_signal_connect_data ((instance), (detailed_signal), (c_handler), (data), NULL,     (GConnectFlags) 0)
                                                                             ^
 Compilation failed.

怎么了？我该怎么办？？？

你能再解释一下第二个论点吗？（英语不是我的母语，这部分对我来说有点困惑：P）

再次感谢。