/*
C#: The Complete Reference 
by Herbert Schildt 

Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Swap two references. 
 
using System; 
 
class RefSwap { 
  int a, b; 
   
  public RefSwap(int i, int j) { 
    a = i; 
    b = j; 
  } 
 
  public void show() { 
    Console.WriteLine("a: {0}, b: {1}", a, b); 
  } 
 
  // This method now changes its arguments. 
  public void swap(ref RefSwap ob1, ref RefSwap ob2) { 
    RefSwap t; 
  
    t = ob1; 
    ob1 = ob2; 
    ob2 = t; 
  } 
} 
 
public class RefSwapDemo { 
  public static void Main() { 
    RefSwap x = new RefSwap(1, 2); 
    RefSwap y = new RefSwap(3, 4); 
 
    Console.Write("x before call: "); 
    x.show(); 
 
    Console.Write("y before call: "); 
    y.show(); 
 
    Console.WriteLine(); 
 
    // exchange the objects to which x and y refer 
    x.swap(ref x, ref y);  
 
    Console.Write("x after call: "); 
    x.show(); 
 
    Console.Write("y after call: "); 
    y.show(); 
 
  } 
} 


           
          

/*
C#: The Complete Reference
by Herbert Schildt

Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Use two out parameters.

using System;

class Num {
/* Determine if x and v have a common denominator.
If so, return least and greatest common denominators in
the out parameters. */
public bool isComDenom(int x, int y,
out int least, out int greatest) {
int i;
int max = x < y ? x : y; bool first = true; least = 1; greatest = 1; // find least and treatest common denominators for(i=2; i <= max/2 + 1; i++) { if( ((y%i)==0) & ((x%i)==0) ) { if(first) { least = i; first = false; } greatest = i; } } if(least != 1) return true; else return false; } } public class DemoOut { public static void Main() { Num ob = new Num(); int lcd, gcd; if(ob.isComDenom(231, 105, out lcd, out gcd)) { Console.WriteLine("Lcd of 231 and 105 is " + lcd); Console.WriteLine("Gcd of 231 and 105 is " + gcd); } else Console.WriteLine("No common denominator for 35 and 49."); if(ob.isComDenom(35, 51, out lcd, out gcd)) { Console.WriteLine("Lcd of 35 and 51 " + lcd); Console.WriteLine("Gcd of 35 and 51 is " + gcd); } else Console.WriteLine("No common denominator for 35 and 51."); } } [/csharp]

   

/*
C#: The Complete Reference 
by Herbert Schildt 

Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Use out. 
 
using System; 
 
class Decompose { 
 
  /* Decompose a floating-point value into its 
      integer and fractional parts. */ 
  public int parts(double n, out double frac) { 
    int whole; 
 
    whole = (int) n; 
    frac = n - whole; // pass fractional part back through frac 
    return whole; // return integer portion 
  } 
} 
  
public class UseOut { 
  public static void Main() {   
   Decompose ob = new Decompose(); 
    int i; 
    double f; 
 
    i = ob.parts(10.125, out f); 
 
    Console.WriteLine("Integer portion is " + i); 
    Console.WriteLine("Fractional part is " + f); 
  } 
}


           
          

   

/*
C#: The Complete Reference 
by Herbert Schildt 

Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Swap two values. 
 
using System; 
 
class Swap { 
  // This method now changes its arguments. 
  public void swap(ref int a, ref int b) { 
    int t; 
  
    t = a; 
    a = b; 
    b = t; 
  } 
} 
 
public class SwapDemo { 
  public static void Main() { 
    Swap ob = new Swap(); 
 
    int x = 10, y = 20; 
 
    Console.WriteLine("x and y before call: " + x + " " + y); 
 
    ob.swap(ref x, ref y);  
 
    Console.WriteLine("x and y after call: " + x + " " + y); 
  } 
}

           
          

   

/*
C#: The Complete Reference 
by Herbert Schildt 

Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Use ref to pass a value type by reference. 
 
using System; 
 
class RefTest { 
  /* This method changes its arguments. 
     Notice the use of ref. */ 
  public void sqr(ref int i) { 
    i = i * i; 
  } 
} 
 
public class RefDemo { 
  public static void Main() { 
    RefTest ob = new RefTest(); 
 
    int a = 10; 
 
    Console.WriteLine("a before call: " + a); 
 
    ob.sqr(ref a); // notice the use of ref 
 
    Console.WriteLine("a after call: " + a); 
  } 
}

           
          

   

/*
C#: The Complete Reference 
by Herbert Schildt 

Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Objects are passed by reference. 
 
using System; 
 
class Test { 
  public int a, b; 
 
  public Test(int i, int j) { 
    a = i; 
    b = j; 
  }
  /* Pass an object. Now, ob.a and ob.b in object 
     used in the call will be changed. */ 
  public void change(Test ob) { 
    ob.a = ob.a + ob.b; 
    ob.b = -ob.b; 
  } 
} 
 
public class CallByRef { 
  public static void Main() { 
    Test ob = new Test(15, 20); 
 
    Console.WriteLine("ob.a and ob.b before call: " + 
                       ob.a + " " + ob.b); 
 
    ob.change(ob); 
 
    Console.WriteLine("ob.a and ob.b after call: " + 
                       ob.a + " " + ob.b); 
  } 
}

           
          

   

/*
C#: The Complete Reference 
by Herbert Schildt 

Publisher: Osborne/McGraw-Hill (March 8, 2002)
ISBN: 0072134852
*/
// Simple types are passed by value. 
 
using System; 
 
class Test { 
  /* This method causes no change to the arguments 
     used in the call. */ 
  public void noChange(int i, int j) { 
    i = i + j; 
    j = -j; 
  } 
} 
 
public class CallByValue { 
  public static void Main() { 
    Test ob = new Test(); 
 
    int a = 15, b = 20; 
 
    Console.WriteLine("a and b before call: " + 
                       a + " " + b); 
 
    ob.noChange(a, b);  
 
    Console.WriteLine("a and b after call: " + 
                       a + " " + b); 
  } 
}