Chapter 8 - Fill In the Code

Question 1

27. This code assigns the value 10 to all the elements of an array a.

int [ ] a = new int[25];
for ( int i = 0; i < a.length; i++ )
{
        // your code goes here
}

Answer 1

a[i]=10;

Question 2

28. This code prints all the elements of array a that have a value greater than 20.

double [ ] a = { 45.2, 13.1, 12.8, 87.4, 99.0, 100.1, 43.8, 2.4 };

for ( int i = 0; i < a.length; i++ )
{
        // your code goes here
}

Answer 2

if(a[i]>20)

Question 3

29. This code prints the average of the elements of array a.

int [ ] a = { 45, 13, 12, 87, 99, 100, 43, 2 };

double average = 0.0;
for ( int i = 0; i < a.length; i++ )
{
        // your code goes here
}
// ... and your code continues here

Answer 3

{
average+=a[i];
}
System.out.println(average/a.length);

Question 4

30. This code calculates and prints the dot product of two arrays (Σ a[i] * b[i]).

int [ ] a = { 3, 7, 9 };
int [ ] b = { 2, 9, 4 };
int dotProduct = 0;

for ( int i = 0; i < a.length; i++ )
{
       // your code goes here
}

Answer 4

{
dotProduct+=a[i]*b[i];
}
System.out.println(dotProduct);

Question 5

31. This code prints the following three lines:

a[0] = 3
a[1] = 6
a[2] = 10

int [ ] a = { 3, 6, 10 };
for ( int i = 0; i < a.length; i++ )
{
       // your code goes here
}

Answer 5

System.out.println(“a[“+i+”] = “+a[i]);

Question 6

32. This method returns true if an element in an array of Strings passed as a parameter contains the substring IBM; otherwise, it returns false.

public boolean foo( String [ ] a )
{
       // your code goes here
}

Answer 6

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

Question 7

33. This method returns the number of elements in an array passed as a parameter that are multiples of 7.

public int foo( int [ ] a )
{
       // your code goes here
}

Answer 7

int count = 0;
for ( int i = 0; i < a.length; i++ )
{
if ( a[i] % 7 == 0 )
count++;
}
return count;

Question 8

34. This method returns true if the first two elements of the array passed as a parameter have the same value; otherwise, it returns false.

public boolean foo( String [ ] a )
{
       // your code goes here
}

Answer 8

if ( a.length < 2 )
return false;
else if ( a[0].equals( a[1] ) )
return true;
else
return false;

Question 9

35. This method takes an array of ints as a parameter and returns an array of booleans. For each element in the parameter array whose value is 0, the corresponding element of the array returned will be assigned false; otherwise, the element will be assigned true.

public boolean [ ] foo(int [ ] a)
{
       // your code goes here
}

Answer 9

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