class Person
{
public string name;
public int age;
}
Person per = new Person();
if (per.name == null)
{
MessageBox.Show("no name");//执行这句
}
else
{
MessageBox.Show(per.name);
}
if (per.age == null)
{
MessageBox.Show("no age");
}
else
{
MessageBox.Show(per.age.ToString());//执行这句,默认值0
}