Chapter 8 - Understanding Code

Question 1

13. What is the output of this code sequence?

double [ ] a = { 12.5, 48.3, 65.0 };
System.out.println( a[1] );

Answer 1

48.3

Question 2

14. What is the output of this code sequence?

int [ ] a = new int [6];
System.out.println( a[4] )

Answer 2

0

Question 3

15. What is the output of this code sequence?

double [ ] a = { 12.5, 48.3, 65.0 };
System.out.println( a.length );

Answer 3

3

Question 4

16. What is the output of this code sequence?

int [ ] a = { 12, 48, 65 };

for ( int i = 0; i < a.length; i++ )
System.out.println( a[i] );

Answer 4

Output of code:
12
48
65

Question 5

17. What is the output of this code sequence?

int [ ] a = { 12, 48, 65 };

for ( int i = 0; i < a.length; i++ )
System.out.println( “a[” + i + “] = “ + a[i] );

Answer 5

Output of code:
a[0] = 12
a[1] = 48
a[2] = 65

Question 6

18. What is the output of this code sequence?

int s = 0;
int [ ] a = { 12, 48, 65 };

for ( int i = 0; i < a.length; i++ )
s += a[i];
System.out.println( “s = “ + s );

Answer 6

Output of code:

s = 125

Question 7

19. What is the output of this code sequence?

int [ ] a = new int[10];

for ( int i = 0; i < a.length; i++ )
a[i] = i + 10;

System.out.println( a[4] );

Answer 7

Output of code:

14

Question 8

20. What is the output of this code sequence?

double [ ] a = { 12.3, 99.6, 48.2, 65.8 };
double temp = a[0];

for ( int i = 1; i < a.length; i++ )
{
  if ( a[i] > temp )
     temp = a[i];
}
System.out.println( temp );

Answer 8

Output of code:

99.6

Question 9

21. What is the output of this code sequence?

int [ ] a = { 12, 48, 65, 23 };
int temp = a[1];
a[1] = a[3];
a[3] = temp;

for ( int i = 0; i < a.length; i++ )
System.out.print( a[i] + “ “ );

Answer 9

Output of code:
12
23
65
48

Question 10

22. What does this method do?

public int foo( int [ ] a )
{
int temp = 0;

   for ( int i = 0; i < a.length; i++ )
   {
         if ( a[i] == 5 )
               temp++;
   }
   return temp;
}

Answer 10

It counts how many elements in the argument array have the value 5

Question 11

23. What does this method do?

public int foo( int [ ] a )
{
     for ( int i = 0; i < a.length; i++ )
     {
            if ( a[i] == 10 )
                 return i;
     }
     return -1;
}

Answer 11

It returns the index of the first element in the argument array with value 10. If no
element in the argument array has value 10, it returns –1.

Question 12

24. What does this method do?

public boolean foo( int [ ] a )
{
     for ( int i = 0; i < a.length; i++ )
     {
            if ( a[i] < 0 )
                 return false;
     }
     return true;
}

Answer 12

If the argument array has at least one element that is negative, it returns false, otherwise it returns
true.

Question 13

25. What does this method do?

public String [ ] foo( String [ ] a )
{
String [ ] temp = new String[a.length];
for ( int i = 0; i < a.length; i++ )
{
temp[i] = a[i].toLowerCase( );
}
return temp;
}

Answer 13

It returns an array of Strings identical to the argument array except that the Strings
are all in lowercase.

Question 14

26. What does this method do?

public boolean [ ] foo( String [ ] a )
{
boolean [ ] temp = new boolean[a.length];

      for ( int i = 0; i < a.length; i++ )
      {
            if (a[i].indexOf( "@" ) != -1 )
                  temp[i] = true;
            else
                  temp[i] = false;
      }
      return temp;
}

Answer 14

It returns an array of booleans as follows: if an element in the argument array
contains the character @, then the corresponding element in the returned array is
set to true, otherwise it is set to false.