How to design login page with gtk3 c++ code? [closed]

Question

I want to design login page with gtk3 c++ code. this is my c++ code:

#include <gtk/gtk.h>


void create_window(GtkWidget *button, gpointer window) {

GtkWidget *win, *label;

//Username and Password to validate credentials
const string USERNAME = "user";
const string PASSWORD = "123456";
string username, password;


//Checking if user's entered credentials are equal to actual USERNAME and PASSWORD 
if (username == USERNAME && password == PASSWORD)
{
    label = gtk_label_new("Username and Password is correct.");
    win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_container_add(GTK_CONTAINER(win), label);
    gtk_widget_show_all(win);
}

else if (username != USERNAME || password != PASSWORD)

{
    label = gtk_label_new("Username and Password is incorrect.");
    win = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_container_add(GTK_CONTAINER(win), label);
    gtk_widget_show_all(win);

}

}

static void destroy(GtkWidget *widget, gpointer data){
gtk_main_quit();
}

int main(int argc, char *argv[]){

GtkWidget *window;
GtkWidget *grid;
GtkWidget *Login_button, *Quit_button;
GtkWidget *u_name;
GtkWidget *pass;
GtkWidget *label_user;
GtkWidget *label_pass;
GtkWidget  *button_container;

gtk_init(&argc, &argv);

window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gtk_window_set_title(GTK_WINDOW(window), "Login page");
gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
gtk_container_set_border_width(GTK_CONTAINER(window), 10);
gtk_window_set_resizable(GTK_WINDOW(window), FALSE); 

grid = gtk_grid_new();
gtk_grid_set_row_spacing(GTK_GRID(grid), 3);
gtk_container_add(GTK_CONTAINER(window), grid);

label_user = gtk_label_new("Username  ");
label_pass = gtk_label_new("Password  ");

u_name = gtk_entry_new();
gtk_entry_set_placeholder_text(GTK_ENTRY(u_name), "Username");
gtk_grid_attach(GTK_GRID(grid), label_user, 0, 1, 1, 1);
gtk_grid_attach(GTK_GRID(grid), u_name, 1, 1, 2, 1);

pass = gtk_entry_new();
gtk_entry_set_placeholder_text(GTK_ENTRY(pass), "Password");
gtk_grid_attach(GTK_GRID(grid), label_pass, 0, 2, 1, 1);
gtk_entry_set_visibility(GTK_ENTRY(pass), 0);
gtk_grid_attach(GTK_GRID(grid), pass, 1, 2, 1, 1);

Login_button = gtk_button_new_with_label("Log in");
g_signal_connect(Login_button, "clicked", G_CALLBACK(create_window), NULL);
gtk_grid_attach(GTK_GRID(grid), Login_button, 0, 3, 2, 1);

Quit_button = gtk_button_new_with_label("Quit");
g_signal_connect(Quit_button, "clicked", G_CALLBACK(gtk_main_quit), NULL);
gtk_grid_attach(GTK_GRID(grid), Quit_button, 0, 4, 2, 1);


gtk_widget_show_all(window);

gtk_main();

return 0;
}

But I can't introduce Username and Password to my code.

For example, Username is Alireza and Password is @12345@.

when I insert Username and Password, If Username and Password was correct, Login page destroy and seconde page (new page) open. But if any of them was incorrect, we should have these messages on new page:
If Username was incorrect, message is: Username is incorrect If Password was incorrect, message is : Password is incorrect.

Answer 1

I don't know if you are using a database but if not you need to create a function as you named in signal "create_window" (g_signal_connect(Login_button, "clicked", G_CALLBACK(create_window), NULL);) inside this function add your checking code

If (Username and Password was correct)
    Login page destroy and seconde page (new page) open

If (Username was correct)
     Username is incorrect 
If (Password was incorrect)
     Password is incorrect.

If that's doesn't work for you replay back and I will write the correct code using gtkmm/c++

this is the function but you need to write the messages

static void create_window (GtkWidget *widget, gpointer data) { if( USERNAME != gtk_entry_get_text (GtkEntry *u_name) ) { //your message dyalog here //g_print ("Username is incorrect. \n"); } if( PASSWORD != gtk_entry_get_text (GtkEntry *pass) ) { //your message dyalog here //g_print ("Password is incorrect.\n"); }

}