Series Programs and break and continue Inside Nested Loops in Java (ICSE Class 9)

Understand Series Programs and break and continue Inside Nested Loops

Series Programs and break and continue Inside Nested Loops: key facts

Term reset

set t = 0 (sum) or f = 1 (product) | at the start of each outer pass

Otherwise terms carry over.

Triangular sums

1 + (1+2) + (1+2+3) for n = 3 | gives 1 + 3 + 6 = 10

Inner loop builds each bracket.

Jumps in nested loops

break and continue | affect only the loop that contains them

The outer loop continues.

Prime flag

• •flag = true
• •divisor found: flag = false and break
• •print if flag still true

Divisors from 2 to n - 1.

Series Programs and break and continue Inside Nested Loops in real life

The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.

Tricks to remember Series Programs and break and continue Inside Nested Loops

Short memory aids. Say each one aloud once, then use it on a question the same day.

• Reset the term

  Start every outer pass with t = 0 or f = 1.

  Use it when: Series programs.

• Break breaks one loop

  break leaves just the loop that holds it.

  Use it when: Nested jumps.

• Flag and break

  A prime check uses a flag that is cleared at the first divisor.

  Use it when: Prime programs.

Series Programs and break and continue Inside Nested Loops: solved examples

Ordered from board level to HOTS. Try each one before you open the solution.

for (int i = 1; i <= 5; i++)
for (int j = 1; j <= 3; j++)
count++;

int s = 0;
for (int i = 1; i <= 3; i++)
{
int t = 0;
for (int j = 1; j <= i; j++)
t = t + j;
s = s + t;
}
System.out.println(s);

int s = 0;
for (int i = 1; i <= 4; i++)
{
int f = 1;
for (int j = 1; j <= i; j++)
f = f * j;
s = s + f;
}
System.out.println(s);

for (int i = 1; i <= 3; i++)
{
for (int j = 1; j <= 3; j++)
{
if (j == i)
break;
System.out.print(j);
}
System.out.println();
}

for (int i = 1; i <= 2; i++)
{
for (int j = 1; j <= 3; j++)
{
if (j == 2)
continue;
System.out.print(i * j + " ");
}
System.out.println();
}

for (int n = 2; n <= 10; n++)
{
boolean prime = true;
for (int d = 2; d < n; d++)
{
if (n % d == 0)
{
prime = false;
break;
}
}
if (prime)
System.out.print(n + " ");
}

Where students lose marks in Series Programs and break and continue Inside Nested Loops

The slips examiners see most often, and what to write instead.

• ✗Mistake: Not resetting the term

  The variable lives outside the outer loop.

  Wrong working

  t declared once before the loops

  Right working

  int t = 0; at the start of every outer pass

  ✓Do this: Reset in the outer loop.

  Usually costs: 2 marks

• ✗Mistake: Assuming break ends both loops

  Single break is misread.

  Wrong working

  break stops the whole nested loop

  Right working

  break stops only the inner loop

  ✓Do this: It affects the nearest loop.

  Usually costs: 2 marks

• ✗Mistake: Missing flag in a prime check

  Printing happens inside the divisor loop.

  Wrong working

  Printing n for every d that does not divide

  Right working

  Use a flag and print after the inner loop

  ✓Do this: Decide after the loop ends.

  Usually costs: 2 marks

Practice questions on Series Programs and break and continue Inside Nested Loops

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQBoard level

   A break statement inside an inner loop terminates:
   (a) the whole program (b) only the inner loop (c) both loops (d) only the current outer pass without leaving the inner loop

   Hint

   It leaves the loop that holds it.

   Answer

   (b) only the inner loop

2. Q2 · 1 mark · Very short answerBoard level

   How many times does the body run for i = 1 to 4 and j = 1 to 4?

   Hint

   Rows times columns.

   Answer

   16

3. Q3 · 3 marks · Short answerHarder board level

   Find the output:

   int s = 0;
   for (int i = 1; i <= 4; i++)
   {
   int p = 1;
   for (int j = 1; j <= i; j++)
   p = p * 2;
   s = s + p;
   }
   System.out.println(s);

   Hint

   p takes 2, 4, 8, 16.

   Answer

   30 (2 + 4 + 8 + 16)

4. Q4 · 3 marks · Short answerHarder board level

   Show the output:

   for (int i = 2; i <= 3; i++)
   {
   for (int j = 1; j <= 3; j++)
   System.out.print(i * j + " ");
   System.out.println();
   }

   Hint

   Multiply i by j.

   Answer

   2 4 6
   3 6 9

5. Q5 · 4 marks · Short answerHOTS / competency

   Write nested loops that print Floyd's triangle of three rows and show the output.

   Hint

   Use a counter k.

   Answer

   int k = 1;
   for (int i = 1; i <= 3; i++)
   {
   for (int j = 1; j <= i; j++)
   {
   System.out.print(k + " ");
   k++;
   }
   System.out.println();
   }
   Output:
   1
   2 3
   4 5 6

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.Sum of 1 + (1+2) + (1+2+3)?Show answer

   10

2. 2.What is 4 factorial?Show answer

   24

3. 3.Which loop does break affect?Show answer

   The nearest enclosing loop.

4. 4.Why use a flag in a prime check?Show answer

   To decide after the divisor loop whether any divisor was found.

5. 5.Divisors tested for n in a simple prime check?Show answer

   2 to n - 1

6. 6.How is Floyd's triangle numbered?Show answer

   With a counter that increases after every print.

Series Programs and break and continue Inside Nested Loops: frequently asked questions