2. Declaring the Loop Control Variable



Answer:
All three aspects of the loop
  1. Initializing the loop,
  2. testing the ending condition, and
  3. changing the value of what is being tested,
are done in one statement. This makes it easier to check if you have done things correctly.






Declaring the Loop Control Variable



    

        

            

                
Here is a counting loop:

            

        

    





    

        

            

                

                    
int count;

. . . . . .

for ( count = 0;  count < 10; count++ ) 
  System.out.print( count + " " );

                

            

        

    





    

        

            

                
The loop control variable count has been declared somewhere in the program, possibly many statements away from the for statement. This violates the idea that all the parts of the loop are combined
                    in one statement. It would be nice if the declaration of count were part of the for statement. In fact, this can be done, as in the following:

            

        

    





    

        

            

                

                    
for ( int count = 0;  count < 10; count++ )
  System.out.print( count + " " );

                

            

        

    





    

        

            

                
In this example, the declaration of count and its initialization have been combined.

            

            

                
However, there is an important difference between this program fragment and the previous one:

                
Annotation 2020-03-19 215454

                
The following is NOT correct:

            

        

    





    

        

            

                

                    
for ( int count = 0;  count < 10; count++ )    
  System.out.print( count + " " );

// NOT part of the loop body
System.out.println( 
  "\nAfter the loop count is: " + count );  

                

            

        

    





    

        

            

                
Since the println() statement is not part of the loop body, count cannot be used here. The compiler will complain that it "cannot find the symbol: count" when it sees this count.
                    This can be a baffling error message if you forget the scope rule.

            

        

    







Question 2:
Is the following code fragment correct?
    int sum = 0;
for ( int j = 0;  j < 8; j++ )
    sum = sum + j;

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