将int传递给C回调

Question

为什么我在回调中无法正确识别？

我想也许是因为在add_strip()"i"被销毁之后,我怎么能把int传递给那个回调呢？谢谢.

29 void add_strip(int i,char name[30]){
30     sl[i] = elm_slider_add(win);
31     elm_slider_label_set(sl[i], name);
32     elm_slider_unit_format_set(sl[i], "dB");
33     elm_slider_span_size_set(sl[i], 60);
34     evas_object_size_hint_align_set(sl[i], 0.5, EVAS_HINT_FILL);
35     evas_object_size_hint_weight_set(sl[i], 0.0, EVAS_HINT_EXPAND);
36     elm_slider_indicator_format_set(sl[i], "%3.0f");
37     elm_slider_min_max_set(sl[i], 0, 2);
38     elm_slider_inverted_set(sl[i], 1);
39     elm_slider_value_set(sl[i], 0);
40     elm_object_scale_set(sl[i], 1.0);
41     elm_slider_horizontal_set(sl[i], 0);
42     elm_box_pack_end(bx, sl[i]);
43     evas_object_show(sl[i]);
44     evas_object_smart_callback_add(sl[i], "changed", vol_changed, &i);  // <--------------
45 }

回调是:

13 static void
14 vol_changed(void *data, Evas_Object *obj, void *event_info)
15 {
16     int n = *((int*)data);
17     printf("%d\n", &n); // <------------------------------------- this prints always -1078364196 (seems an address)
18
19     if(lo_send(dest, "/fader/0", "f", elm_slider_value_get(sl[0]))==-1)
20         printf("OSC error %d: %s\n", lo_address_errno(dest), lo_address_errstr(d    est));
21 }

Answer 1

您将局部变量的地址作为参数传递给回调.因此,当函数退出时,变量被释放.它的地址现在无效.当调用回调时,局部变量的地址很可能被其他东西使用,这解释了奇怪的(和不同的)值.

此外,正如其他帖子中所述,您错误地键入了您的剪辑.