Create a specifiable range array class : Indexer : Class Interface C# Source Code

    

/*
C#: The Complete Reference 
by Herbert Schildt 

Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/

/* Create a specifiable range array class. 
   The RangeArray class allows indexing 
   to begin at some value other than zero. 
   When you create a RangeArray, you specify 
   the beginning and ending index. Negative 
   indexes are also  allowed.  For example, 
   you can create arrays that index from -5 to 5,  
   1 to 10, or 50 to 56. 
*/ 
  
using System;  
  
class RangeArray {   
  // private data 
  int[] a; // reference to underlying array   
  int lowerBound; // lowest index 
  int upperBound; // greatest index 
 
  // data for properties 
  int len; // underlying var for Length property 
  bool errflag; // underlying var for outcome  
    
  // Construct array given its size.  
  public RangeArray(int low, int high) {  
    high++; 
    if(high <= low) { 
      Console.WriteLine("Invalid Indices"); 
      high = 1; // create a minimal array for safety 
      low = 0; 
    } 
    a = new int[high - low];  
    len = high - low;   
 
    lowerBound = low; 
    upperBound = --high; 
  }  
  
  // Read-only Length property.  
  public int Length {  
    get {  
      return len;  
    }  
  }  
 
  // Read-only Error property.  
  public bool Error {  
    get {  
      return errflag;  
    }  
  }  
 
  // This is the indexer for RangeArray.  
  public int this[int index] {  
    // This is the get accessor.  
    get {  
      if(ok(index)) {  
        errflag = false;  
        return a[index - lowerBound];  
      } else {  
        errflag = true;  
        return 0;  
      }  
    }  
  
    // This is the set accessor  
    set {  
      if(ok(index)) {  
        a[index - lowerBound] = value;  
        errflag = false;  
      }  
      else errflag = true;  
    }  
  }  
  
  // Return true if index is within bounds.  
  private bool ok(int index) {  
    if(index >= lowerBound & index <= upperBound) return true;  
    return false;  
  }  
}   
   
// Demonstrate the index-range array.  
public class RangeArrayDemo {   
  public static void Main() {   
    RangeArray ra = new RangeArray(-5, 5);  
    RangeArray ra2 = new RangeArray(1, 10);  
    RangeArray ra3 = new RangeArray(-20, -12);  
 
    // Demonstrate ra 
    Console.WriteLine("Length of ra: " + ra.Length); 
 
    for(int i = -5; i <= 5; i++) 
      ra[i] = i; 
   
    Console.Write("Contents of ra: "); 
    for(int i = -5; i <= 5; i++) 
      Console.Write(ra[i] + " "); 
 
    Console.WriteLine("\n"); 
 
    // Demonstrate ra2 
    Console.WriteLine("Length of ra2: " + ra2.Length); 
 
    for(int i = 1; i <= 10; i++) 
      ra2[i] = i; 
 
    Console.Write("Contents of ra2: "); 
    for(int i = 1; i <= 10; i++) 
      Console.Write(ra2[i] + " "); 
 
    Console.WriteLine("\n"); 
 
    // Demonstrate ra3 
    Console.WriteLine("Length of ra3: " + ra3.Length); 
 
    for(int i = -20; i <= -12; i++) 
      ra3[i] = i; 
 
    Console.Write("Contents of ra3: "); 
    for(int i = -20; i <= -12; i++) 
      Console.Write(ra3[i] + " "); 
 
    Console.WriteLine("\n"); 
 
  }  
}