Question

我尝试使用整数值更新标签，具体取决于我是按减号还是添加按钮。但是它没有工作，我很确定它与我如何通过我的 GTK_LABEL（总和）有关，而我正试图更新它。< / p>

之前的工作是将地址传递给按钮功能的int，然后通过this question的最佳答案 g_print 将其传入终端。

以下是完整的error message，此处是我的代码。

#include <gtk/gtk.h>
#include <string.h>


void updateLabel(GTK_LABEL(sum), int num)
{
    gchar *display;
    display = g_strdup_printf("%d", num);         //convert num to str
    gtk_label_set_text (GTK_LABEL(sum), display); //set label to "display"
    g_free(display);                              //free display
}


void buttonAdd (GtkButton *button, GtkLabel *sum, gpointer num)
{
    num += 1;
    g_print("%i\n",num);
    updateLabel(GTK_LABEL(sum),num);
}

void buttonSub (GtkButton *button, GtkLabel *sum, gpointer num)
{ 
    num -= 1;
    g_print("%i\n",num);
    updateLabel(GTK_LABEL(sum),num);
}


int main (int argc, char **argv)
{
    signed int n = 0;
    char display = n;
    GtkWidget *window;
    GtkWidget *addButton;
    GtkWidget *subButton;  
    GtkWidget *grid;
    GtkWidget *sum;

    gtk_init (&argc,&argv);

    //Declarations
    window    = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    sum       = gtk_label_new (&display);
    grid      = gtk_grid_new ();
    addButton = gtk_button_new_with_label ("Add Value");
    subButton = gtk_button_new_with_label ("Sub Value");

    //Set Properties
    gtk_container_set_border_width (GTK_CONTAINER(window), 20);
    gtk_widget_set_size_request    (GTK_CONTAINER(window), 150, 100);
    gtk_label_set_selectable       (GTK_LABEL(sum), TRUE);
    gtk_grid_set_row_spacing       (GTK_GRID(grid), 4);
    gtk_grid_set_column_spacing    (GTK_GRID(grid), 4);
    gtk_container_add              (GTK_CONTAINER(window), grid);

    //Fill the grid with shit                  (x, y, h, v)
    gtk_grid_attach (GTK_GRID(grid), addButton, 0, 0, 1, 1);
    gtk_grid_attach (GTK_GRID(grid), subButton, 1, 0, 1, 1); 
    gtk_grid_attach (GTK_GRID(grid), sum,       0, 2, 2, 1);

    gtk_widget_show_all (window);

    g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL);
    g_signal_connect(G_OBJECT(addButton), "clicked", G_CALLBACK(buttonAdd), &n);
    g_signal_connect(G_OBJECT(subButton), "clicked", G_CALLBACK(buttonSub), &n);
    gtk_main();

    return 0;
}

我认为重要的是要注意我是C的新手，而且我来自python，因此指针，地址和GTK语法对我来说非常神秘。简单的非jargony GTK指南似乎也不存在于互联网上。如果有人可以告诉我我做错了什么，或者展示一个更好的方式，那就太棒了!! 谢谢！

Answer 1

我将您的代码修改为按照您的描述工作：

#include <gtk/gtk.h>
#include <string.h>
#include <stdlib.h>

void updateLabel(GtkLabel *sum, int num)
{
    gchar *display;
    display = g_strdup_printf("%d", num);         //convert num to str
    gtk_label_set_text (GTK_LABEL(sum), display); //set label to "display"
    g_free(display);                              //free display
}

void buttonAdd (GtkButton *button, GtkLabel *sum)
{
    int num = atoi(gtk_label_get_text(sum));
    num += 1;
    g_print("%d\n",num);
    updateLabel(GTK_LABEL(sum), num);
}

void buttonSub (GtkButton *button, GtkLabel *sum)
{
    int num = atoi(gtk_label_get_text(sum));
    num -= 1;
    g_print("%i\n",num);
    updateLabel(GTK_LABEL(sum),num);

}

int main(int argc, char **argv)
{
    GtkWidget *window;
    GtkWidget *addButton;
    GtkWidget *subButton;
    GtkWidget *grid;
    GtkWidget *sum;

    gtk_init (&argc,&argv);

    //Declarations
    window    = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    sum       = gtk_label_new ("0");
    grid      = gtk_grid_new ();
    addButton = gtk_button_new_with_label ("Add Value");
    subButton = gtk_button_new_with_label ("Sub Value");

    //Set Properties
    gtk_container_set_border_width (GTK_CONTAINER(window), 20);
    gtk_widget_set_size_request    (GTK_WIDGET(window), 150, 100);
    gtk_label_set_selectable       (GTK_LABEL(sum), TRUE);
    gtk_grid_set_row_spacing       (GTK_GRID(grid), 4);
    gtk_grid_set_column_spacing    (GTK_GRID(grid), 4);
    gtk_container_add              (GTK_CONTAINER(window), grid);

    //Fill the grid with shit                  (x, y, h, v)
    gtk_grid_attach (GTK_GRID(grid), addButton, 0, 0, 1, 1);
    gtk_grid_attach (GTK_GRID(grid), subButton, 1, 0, 1, 1);
    gtk_grid_attach (GTK_GRID(grid), sum,       0, 2, 2, 1);

    gtk_widget_show_all (window);

    g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL);
    g_signal_connect(G_OBJECT(addButton), "clicked", G_CALLBACK(buttonAdd), sum);
    g_signal_connect(G_OBJECT(subButton), "clicked", G_CALLBACK(buttonSub), sum);

    gtk_main();

    return 0;
}

从一开始：

虽然char可以用作int，但是不能简单地通过char display = n;将整个int转换为字符串，因为每个char都有自己的值与它们所代表的字符相关联（http://www.asciitable.com/ ）。字符串（char *或char []）由字符表组成。
按钮的信号函数buttonAdd()和buttonSub包含两个参数而不是三个：第一个是引发信号的gtk小部件的指针，第二个参数是在来自g_signal_connect()函数的最后一个参数。通常我们会通过指针传递大量数据，所以在这种情况下我们会创建一个struct变量，填充它并传递它，但在你的情况下，只需传递gtk标签，因为它已经包含我们可以阅读并增加/减少它的字符串。
我使用atoi（）将字符串转换为int，但对于更强大的解决方案，最好使用strtol，但对于你的例子atoi（）绰绰有余。
您不能将GTK_LABEL（）用作参数，因为它是宏而不是类型。

获取GTK标签以在C中显示int

1 个答案: