Use an indexer to create a fail-soft array : Indexer : Class Interface C# Source Code

    

/*
C#: The Complete Reference 
by Herbert Schildt 

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

// Use an indexer to create a fail-soft array. 
 
using System; 
 
class FailSoftArray {  
  int[] a;    // reference to underlying array  
 
  public int Length; // Length is public 
 
  public bool errflag; // indicates outcome of last operation 
   
  // Construct array given its size. 
  public FailSoftArray(int size) { 
    a = new int[size]; 
    Length = size;  
  } 
 
  // This is the indexer for FailSoftArray. 
  public int this[int index] { 
    // This is the get accessor. 
    get { 
      if(ok(index)) { 
        errflag = false; 
        return a[index]; 
      } else { 
        errflag = true; 
        return 0; 
      } 
    } 
 
    // This is the set accessor 
    set { 
      if(ok(index)) { 
        a[index] = value; 
        errflag = false; 
      } 
      else errflag = true; 
    } 
  } 
 
  // Return true if index is within bounds. 
  private bool ok(int index) { 
   if(index >= 0 & index < Length) return true; 
   return false; 
  } 
}  
  
// Demonstrate the fail-soft array. 
public class FSDemo {  
  public static void Main() {  
    FailSoftArray fs = new FailSoftArray(5); 
    int x; 
 
    // show quiet failures 
    Console.WriteLine("Fail quietly."); 
    for(int i=0; i < (fs.Length * 2); i++) 
      fs[i] = i*10; 
 
    for(int i=0; i < (fs.Length * 2); i++) { 
      x = fs[i]; 
      if(x != -1) Console.Write(x + " "); 
    } 
    Console.WriteLine(); 
 
    // now, generate failures 
    Console.WriteLine("\nFail with error reports."); 
    for(int i=0; i < (fs.Length * 2); i++) { 
      fs[i] = i*10; 
      if(fs.errflag) 
        Console.WriteLine("fs[" + i + "] out-of-bounds"); 
    } 
 
    for(int i=0; i < (fs.Length * 2); i++) { 
      x = fs[i]; 
      if(!fs.errflag) Console.Write(x + " "); 
      else 
        Console.WriteLine("fs[" + i + "] out-of-bounds"); 
    } 
  } 
}