C# 0 The Complete Reference

PART I

C h a p t e r   1 8 :  

G e n e r i c s  

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PART IPART I

    // Copy src to target, inserting e at idx in the process.

    for(int i=0, j=0; i < src.Length; i++, j++) {

      if(i == idx) {

        target[j] = e;

        j++;

      }

      target[j] = src[i];

    }

    return true;

  }

}

class GenMethDemo {

  static void Main() {

    int[] nums = { 1, 2, 3 };

    int[] nums2 = new int[4];

    // Display contents of nums.

    Console.Write("Contents of nums: ");

    foreach(int x in nums)

      Console.Write(x + " ");

    Console.WriteLine();

    // Operate on an int array.

    ArrayUtils.CopyInsert(99, 2, nums, nums2);

    // Display contents of nums2.

    Console.Write("Contents of nums2: ");

    foreach(int x in nums2)

      Console.Write(x + " ");

    Console.WriteLine();

    // Now, use copyInsert on an array of strings.

    string[] strs = { "Generics", "are", "powerful."};

    string[] strs2 = new string[4];

    // Display contents of strs.

    Console.Write("Contents of strs: ");

    foreach(string s in strs)

      Console.Write(s + " ");

    Console.WriteLine();

    // Insert into a string array.

    ArrayUtils.CopyInsert("in C#", 1, strs, strs2);

    // Display contents of strs2.

    Console.Write("Contents of strs2: ");

    foreach(string s in strs2)

      Console.Write(s + " ");

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526

 

P a r t   I :  

T h e   C #   L a n g u a g e

    Console.WriteLine();

    // This call is invalid because the first argument

    // is of type double, and the third and fourth arguments

    // have element types of int.

//    ArrayUtils.CopyInsert(0.01, 2, nums, nums2);

  }

}

The output from the program is shown here:

Contents of nums: 1 2 3

Contents of nums2: 1 2 99 3

Contents of strs: Generics are powerful.

Contents of strs2: Generics in C# are powerful.

Let’s examine 

CopyInsert( )

 closely. First, notice how it is declared by this line:

public static bool CopyInsert(T e, uint idx,

                                 T[] src, T[] target) {

The type parameter is declared 

after

 the method name, but 

before

 the parameter list. Also 

notice that 

CopyInsert( )

 is static, enabling it to be called independently of any object. 

Understand, though, that generic methods can be either static or non-static. There is no 

restriction in this regard.

Now, notice how