C经典案例

Posted 2020-11-07 hellokitty2

1. C中可变参数函数作为函数参数：

void media_debug_set_handler(struct media_device *media, void (*debug_handler)(void *, ...), void *debug_priv)
调用：
media_debug_set_handler(media, (void (*)(void *, ...))fprintf, stdout);

 

2.可变参数函数

gstcaps.c

GstCaps *gst_caps_new_full (GstStructure * struct1, ...)
{
  GstCaps *caps;
  va_list var_args;

  va_start (var_args, struct1);
  caps = gst_caps_new_full_valist (struct1, var_args);
  va_end (var_args);

  return caps;
}

GstCaps * gst_caps_new_full_valist (GstStructure * structure, va_list var_args)
{
  GstCaps *caps;

  caps = gst_caps_new_empty ();

  while (structure) {
    gst_caps_append_structure_unchecked (caps, structure);
    structure = va_arg (var_args, GstStructure *);
  }

  return caps;
}