code
https://docs.gtk.org/gtk3

Template

**main method way**
```c
#include <gtk/gtk.h>
#include <stdio.h>

void gtk_main_quit1()
{
    gtk_main_quit();
    printf("Inside quit");
}

int main(int argc,char **argv)
{
    printf("hello world 12");

    gtk_init(&argc,&argv);
    int a=12;
    int b=13;

    GtkWidget *window;

    // gtk_window_new(type) here type can be pop window or top level
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

    // callback function
    // 1st para is instance,2nd is detail,3rd is callback function handler, 4th is data to be passed to call back function
    // gtk_main_quit will quit the gtk_main program
    g_signal_connect(window,"destroy",G_CALLBACK(gtk_main_quit1),NULL);

    



    // show all gtk widgets that are created. window is parent widget
    gtk_widget_show_all(window);



    
    

    gtk_main();

    
    return 0;
}

```


Compile it with 
```bash
gcc `pkg-config --cflags gtk+-3.0` -o main1 main.c `pkg-config --libs gtk+-3.0`
```

Run it with `./main1`
&nbsp;
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Better without infinite loop(**gtk application way**)

```c
#include <gtk/gtk.h>

static void activate(GtkApplication *app,gpointer user_data)
{
    // gtk code comes here
    GtkWidget *window;

    window= gtk_application_window_new(app);

    gtk_widget_show_all(window);
}

int main(int argc,char **argv)
{
    
    GtkApplication *app;
    int ret; 
    int as=12;

    // 1st para ie application name should have atleast one dot(.) character
    app= gtk_application_new("in.firstApp23",G_APPLICATION_FLAGS_NONE); // G_APPLICATION_FLAGS_NONE is enum whose value is 0
    // app= gtk_application_new("firstApp",G_APPLICATION_DEFAULT_FLAGS);
    g_signal_connect(app,"activate",G_CALLBACK(activate),NULL);
    ret=g_application_run(G_APPLICATION(app),argc,argv);

    g_object_unref(app);

    return ret;

    
 
    

}
```

here `app` argument in   `g_application_run`  have to be type casted using `G_APPLICATION(app)` and `activate` function in gtk_application_new too have to be type casted using `G_CALLBACK(activate)`