類別物件的複製：
(1) 設今有person類別如下：
class person
{
public string name;
public int age;
public person(string n_, int a_) //建構式在此
{ name = n_; age = a_; }
public string self_introduction()
{ return "hi, I'm " + name + "," + age + "years old."; }
};
且已宣告一個person類別物件p1：
person p1 = new person("weiwei", 18);
那麼要如何複製p1呢？
並不是只用person p2 = p1;就可複製p1，因為C#類別物件事實上只是個「參考」，並非「實體」。也就是說，p2和p1參考同一個物件，所以改變p2的同時也會改變p1。證明如下：
person p1 = new person("weiwei", 18);
person p2 = p1;
p2.name = "nunu";
richTextBox1.Text = p1.name.ToString();
則程式執行完成後，richTextBox1.Text之值會是nunu。
(2) 要在C#中執行真正的複製，也就是複製一個與原先物件有相同成員值、成員函數，但互相獨立、彼此互不影響的物件，必須用「深複製(deep copy)」方法。也就是說在類別中自寫一個函式，可回傳一個相同類別物件，而此類別物件與本物件一模一樣。如在person類別中，寫下deep_copy()函式：
public person deep_copy()
{
person new_person = new person(this.name, this.age);
return new_person;
}
然後：
person p1 = new person("weiwei", 18);
person p2 = p1.deep_copy();
p2.name = "nunu";
richTextBox1.Text = p1.name.ToString();
則程式執行完成後，richTextBox1.Text之值還是weiwei。
(3) 深複製並非只有這麼簡單，若碰上更複雜的類別，那就會變得更麻煩。如在上例中再加上一個kingdom類別：
class kingdom
{
public person king;
public person queen;
public List<person> worker = new List<person>();
public string name;
public string history;
public int money;
public kingdom(string name_)
{ name = name_; }
}
那麼在寫深複製函式之前，要先搞清楚哪些成員是類別物件，要先為這些成員寫深複製函式才行。kingdom類別的深複製函式如下：
public kingdom deep_copy()
{
kingdom new_k = new kingdom(this.name);
new_k.king = this.king.deep_copy();
new_k.queen = this.queen.deep_copy();
new_k.worker = this.worker.ToList();
new_k.history=this.history;
new_k.money = this.money;
return new_k;
}
然後利用下列程式碼測試：
kingdom k1 = new kingdom("AAA");
k1.king = new person("king.AAA", 50);
k1.queen = new person("queen.AAA", 40);
k1.worker.Add(new person("w1.AAA", 20));
k1.worker.Add(new person("w2.AAA", 25));
k1.history = "AAA's history";
k1.money = 100;
kingdom k2 = k1.deep_copy();
k2.king = new person("king.BBB", 50);
k2.queen = new person("queen.BBB", 40);
k2.worker.Add(new person("w1.BBB", 20));
k2.worker.Add(new person("w2.BBB", 25));
k2.history = "BBB's history";
k2.money = 200;
richTextBox1.Text +=
"k1:king = " + k1.king.name + "\r\n" +
"k1:queen = " + k1.queen.name + "\r\n" +
"k1:worker = ";
for (int i=0;i<k1.worker.Count;i++)
{
richTextBox1.Text +=k1.worker[i].name+",";
}
richTextBox1.Text += "\r\n" +
"k1:history = " + k1.history + "\r\n" +
"k1:money = " + k1.money + "\r\n";
則程式執行完成後，richTextBox1.Text之值為：
k1:king = king.AAA
k1:queen = queen.AAA
k1:worker = w1.AAA,w2.AAA,
k1:history = AAA's history
k1:money = 100
這代表深複製函式的成功。
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