loop

Question 1

identify what would ‘i’ be at the end of the code in:

for ( int i = 1 ; i <= 3 ; i++ )

Answer 1

4

Question 2

correct the following:

for ( int i = 1 ; i <= 3 ; i++ );

Answer 2

for ( int i = 1 ; i <= 3 ; i++ ) // the for command comes without the ;

Question 3

print the output of the following:
for ( int i = 1 ; i <= 3 ; i++ )
System.out.println(“Hello”);

System.out.println(“end.”);

Answer 3

hello
hello
hello
end.

Question 4

print the output of the following:
for ( int i = 1 ; i <= 3 ; i++ )
{
System.out.println(“Hello”);

System.out.println(“end.”);
}

Answer 4

hello
end.
hello
end.
hello
end.

Question 5

print the output of the following:
for ( int i = 1 ; i <= 3 ; i++ ) ;
{
System.out.println(“Hello”);
System.out.println(“end.”);

Answer 5

hello
end.

Question 6

print the output of the following:
for ( int i = 1 ; ; i++ ) ;
{
System.out.println(“Hello”);

Answer 6

infinite loop.
it will go on forever since there is no condition statement.

Question 7

print the output of the following:

for (int i = 1 ; i <= 9 ; i += 2)

System.out.println(i + “”)

Answer 7

1
3
5
7
9

Question 8

print the output of the following:
for ( int i = 1 ; i <= 10 ; i– )
System.out.print(“*”);

Answer 8

• infinite

Question 9

convert the following to a while code:
// read 3 grads from user then find sum and average :
102
103 int sum = 0 ;
104
105 int num ;
106
107 for(int i = 1 ; i <= 3 ; i++)
108 {
109 System.out.println(“Enter number : “);
110 num = input.nextInt() ;
111 sum = sum + num ;
112
113 }
114
115 System.out.println(“sum = “ +sum );
116 System.out.println(“Average = “ + ( sum / 3 ));

Answer 9

120 int sum = 0 ;
121
122 int num ;
123 int i = 1;
124
125 while( i <= 3 )
126 {
127 System.out.println(“Enter number : “);
128 num = input.nextInt()
129 sum = sum + num ;
130 i++ ;
131 }
132
133 System.out.println(sum );
134 System.out.println(“Average = “ + ( sum / 3 ));

Question 10

What do you use when the question asks you to read a cont. set of numbers but asks to stop at a certain num/char/etc.

Answer 10

it is an essential loop.

Question 11

explain why we added num = input.nextInt() twice in:
System.out.println(“Enter number, to stop enter -1”);
num = input.nextInt();

while ( num != -1)
{
sum = sum + num ;
System.out.println(“Enter number, to stop enter -1”);
num = input.nextInt();
}

Answer 11

we added a second num input in the while loop so that the user can keep entering a number
whereas if we only had the first one then the user wouldve only been able to enter a num once

Question 12

if you were using a do-while code then you must first identify.. before the “do”

Answer 12

the variable that’s within the while condition statement before the do
ex:
char ch;

do(

Question 13

correct the following:

do(
char ch = ‘a’;

double book = 0;
int i;

…….
)while ( int => 0 )

Answer 13

int i;

do(
char ch = ‘a’;

double book = 0;

…….
)while ( int => 0 )

\ you must identify the var used in the while condition statement before the “do”

Question 14

T/F: a ‘break’ could make you exit an if statement.

Answer 14

F, it makes you exit a for or while loop

Question 15

what does the break do?

Answer 15

it immediately takes you out of the loop

Question 16

print the output:

for (int i = 1 ; i <= 5 ; i++)
{
System.out.print(“*”);
if (i == 3)
break;

System.out.println(i);

Answer 16

*1
*2
*

Question 17

if the question asks us to “ignore” instead of “stop” we use (break/continue)

Answer 17

continue

Question 18

what is the most appropriate loop type to use when you are asked to read a GIVEN CERTAIN amount of numbers?
(this is a tip)

Answer 18

for loop

Question 19

print the output of the following:
for (int i = 1 ; i <= 5 ; i++)
{
System.out.print(“*”);
if (i == 3)
continue;

System.out.println(i);

}

Answer 19

*1
*2
**4
*5

Question 20

what’s the difference between a break and continue loop

Answer 20

a break loop immediately takes you out the loop and doesn’t continue it.
a continue loop, essentially only skips/ignores the one condition set before it in the if statement but continues the loop until the end.

Question 21

what’s the difference between a break and continue loop

Answer 21

a break loop immediately takes you out the loop and doesn’t continue it.
a continue loop, essentially only skips/ignores the one condition set before it in the if statement but continues the loop until it ends.

Question 22

When drawing in loop, there will be two “for” statements: the first is for the number of ________, and the second “for” statement is for the number of __________.

Answer 22

the number of lines, the number of whatever symbol we’re printing

Question 23

what is the code for drawing a triangle:

Answer 23

for( int i = 1 ; i <= 4 ; i++)
{
for( int j = 1 ; j <= i ; j++)
System.out.print(“*”);

System.out.println();
}

Question 24

what is a flag loop/what the code?

Answer 24

boolean [variable name] = [identify it as true or false (ex: true)]

while ( [boolean variable] )
{

for loop
[variable name] = [the opposite of what we set it as (ex: false)]

}

Question 25

What is included/we use in a menu code?

Answer 25

do-while code with switch

Question 26

what does this code to a sentence?
for(int i = str.length() - 1 ; i >= 0 ; i– )
System.out.print(str.charAt(i));

Answer 26

reverse it

Question 27

what is the code for printing a number in reverse order?

Answer 27

while ( num != 0 )
{
System.out.print( num % 10);
num = num / 10;
}

System.out.println();

Question 28

what is the code for printing the factorial of a num?

Answer 28

System.out.println(“Enter number to print it’s factorial:”);
int num = read.nextInt();

int fact = 1 ;

for (int i = 1; i <= num ; i++)
fact = fact * i;

System.out.println(“factorial of” + num + “=” + fact) ;

Question 29

loop example that includes strings:
for loop will start with int 0 or 1?

Answer 29

it will start with 0.
for (int i = 0 ; ; )
because we usually have to find the index.