Call by Value (Review)

public class UnitTestTwo
{
  
  public static long factorial( int N )
  {
    long fct = 1;
    for ( int j=1; j<=N; j++ )
      fct *= j;
    return fct;
  }
  
  public static long factorialAlt( int N )
  {
    long fct = 1;
    while ( N>0 )
    {
      fct *= N;
      N-- ;
    }
    return fct;
  }
  
  public static void main (String[] args ) 
  {
     int N = 10;
     System.out.println( "factorial of " + N );
     System.out.println( "scnd  method : " + factorialAlt( N ));
     System.out.println( "first method : " + factorial( N ) ); 
  }
}



C:\Source> java UnitTestTwo
factorial of 10
scnd  method : 3628800
first method : 3628800
C:\Source>

The new program (above) includes two static methods. Of course, this is fine. You can have as many static methods as needed. The new static method also uses N for the name of its formal parameter. This is not a problem. The scope of that N is just that method's body. The new N does not interfere with the others.

Note in particular that the new method factorialAlt() changes the value in its N as it executes. This is fine. N in main() is a totally different variable and keeps the value that was put in it.

QUESTION 11:

Examine the following. Does this code compile? Pay particular attention to N.

public class UnitTestBad
{
  int N = 10;
  
  public static long factorial()
  {
    long fct = 1;
    for ( int j=1; j<=N; j++ )
      fct *= j;
    return fct;
  }
  
  public static void main (String[] args ) 
  {
     System.out.println( "factorial of " + N + ": " + factorial( N ) );
  }
}

Answer:

Call by Value (Review)

QUESTION 11: