5. Keep things local



Answer:
No. The second for loop is trying to use a variable j that is not defined at that point. 
(The first for statement declares a j than can only be seen within that loop.)


    
        

        

        

            
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Keep things local



    

        

        

        

            

        

    




Here is another version of the program, which is syntactically correct, but is not nicely done.




    
        

        

        

            
                

                
public class FoolishTypist
{
  public static void main ( String[] args )
  {
    int sumEven = 0;
    int sumOdd  = 0;
    int j;     // Same "j" used for both loops.

    for ( j = 0;  j < 8; j=j+2 )
        sumEven = sumEven + j;

    System.out.println( "The sum of evens is: " + sumEven ); 

    for ( j = 1;  j < 8; j=j+2 ) 
        sumOdd  = sumOdd + j;                     

    System.out.println( "The sum of odds is: " + sumOdd );
  } 
}

            		
        

    


It is best to keep sections of code self-contained. With this (unwise) version, both loops depend on something distant from themselves. Although this program is clear enough, a longer program might be harder to understand. Here, for instance,
is a typical hard to understand program:



    
        

        

        

            
                
public class FoolishTypist
{
  public static void main ( String[] args )
  {
    int sumEven = 0;
    int sumOdd  = 0;
    int j = 0;
    int i = 1;

    for ( j = 0;  j < 8; j=j+2 )
        sumEven = sumEven + j;

    System.out.println( "The sum of evens is: " + sumEven ); 

    for ( i = 1;  i < 8; i=i+2 ) 
        sumOdd  = sumOdd + j;                     

    System.out.println( "The sum of odds is: " + sumOdd );
  } 
}

            		
        

    







Question 5:
  1. Will this new program compile?
  2. Will it run?
  3. Is it correct?