using System;
string[] array = { "a", "b", "c" };
string[] cloned = array.Clone() as string[];
Console.WriteLine(string.Join(",", array));
Console.WriteLine(string.Join(",", cloned));
Console.WriteLine();
// Change the first element in the cloned array.
cloned[0] = "?";
Console.WriteLine(string.Join(",", array));
Console.WriteLine(string.Join(",", cloned));a,b,c
a,b,c
a,b,c
?,b,c
Example 2. Next we consider the implementation of Clone. The Array.Clone static method is called. And internally Array.Clone calls into MemberwiseClone.
Also System.Array implements System.ICloneable. This is how the runtime knows to pass a call to Clone to the System.Array type.
IL_0022: callvirt instance object [mscorlib]System.Array::Clone()IL_0001: call instance object System.Object::MemberwiseClone().method public hidebysig newslot abstract virtual
instance object Clone() cil managed
{
} // end of method ICloneable::Clone
Example 3. The Rock class implements ICloneable, and defines the Clone() public method. This is probably not "good" code, but if Clone is wanted for some reason, it will work.
Next We create a new instance of the Rock class with its public constructor. We pass three arguments to it.
using System;
class Rock : ICloneable
{
int _weight;
bool _round;
bool _mossy;
public Rock(int weight, bool round, bool mossy)
{
this._weight = weight;
this._round = round;
this._mossy = mossy;
}
public object Clone()
{
return new Rock(this._weight, this._round, this._mossy);
}
public override string ToString()
{
return string.Format("weight = {0}, round = {1}, mossy = {2}",
this._weight,
this._round,
this._mossy);
}
}
class Program
{
static void Main()
{
Rock rock1 = new Rock(10, true, false);
Rock rock2 = rock1.Clone() as Rock;
Console.WriteLine("1. {0}", rock1);
Console.WriteLine("2. {0}", rock2);
}
}1. weight = 10, round = True, mossy = False
2. weight = 10, round = True, mossy = False
Discussion. Clone has some problems. The main issue is the question of shallow and deep copies. ICloneable does not define which kind of cloning is done.
So The developers using Clone are left guessing. This works against the whole point of interfaces, which is to define contracts.
A summary. We explored Clone() and the ICloneable interface. It is difficult to use this interface correctly—using custom methods is clearer.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on May 21, 2023 (simplify).