Module 5 - Looping Structures

5.1 Module Overview

Looping structures allow a program to repeat a task multiple times without rewriting the same code. Loops are used for counting, processing records, validating input, calculating totals, printing patterns and automating repetitive operations.

This module explains looping structures in C, C++, Java and Python. The logic is similar across all four languages, but the syntax differs.

Learning Outcome: Develop repetitive processing using loops in C, C++, Java and Python.

5.2 Syntax Comparison

Concept	C / C++ / Java	Python
for loop	`for (int i=1; i<=5; i++) { }`	`for i in range(1,6):`
while loop	`while (condition) { }`	`while condition:`
break	`break;`	`break`
continue	`continue;`	`continue`
pass	Not available as a direct keyword	`pass`

5.3 for Loop

A for loop is used when the number of repetitions is known. For example, printing numbers from 1 to 5.

C

#include <stdio.h>
int main() {
    for (int i = 1; i <= 5; i++) {
        printf("%d\n", i);
    }
    return 0;
}

C++

#include <iostream>
using namespace std;
int main() {
    for (int i = 1; i <= 5; i++) {
        cout << i << endl;
    }
    return 0;
}

Java

public class Main {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            System.out.println(i);
        }
    }
}

Python

for i in range(1, 6):
    print(i)

Online Working Example

C C++ Java Python

Print numbers from 1 to

Select language and click Run.

5.4 while Loop

A while loop repeats as long as a condition is true. It is useful when the number of repetitions may depend on a condition.

C

#include <stdio.h>
int main() {
    int i = 1;
    while (i <= 5) {
        printf("%d\n", i);
        i++;
    }
    return 0;
}

C++

#include <iostream>
using namespace std;
int main() {
    int i = 1;
    while (i <= 5) {
        cout << i << endl;
        i++;
    }
    return 0;
}

Java

public class Main {
    public static void main(String[] args) {
        int i = 1;
        while (i <= 5) {
            System.out.println(i);
            i++;
        }
    }
}

Python

i = 1
while i <= 5:
    print(i)
    i += 1

Online Working Example

C C++ Java Python

Countdown from

Select language and click Run.

5.5 Nested Loops

A nested loop is a loop inside another loop. It is commonly used for tables, grids, patterns and matrix-style processing.

C

#include <stdio.h>
int main() {
    for (int row = 1; row <= 3; row++) {
        for (int col = 1; col <= 3; col++) {
            printf("* ");
        }
        printf("\n");
    }
    return 0;
}

C++

#include <iostream>
using namespace std;
int main() {
    for (int row = 1; row <= 3; row++) {
        for (int col = 1; col <= 3; col++) {
            cout << "* ";
        }
        cout << endl;
    }
    return 0;
}

Java

public class Main {
    public static void main(String[] args) {
        for (int row = 1; row <= 3; row++) {
            for (int col = 1; col <= 3; col++) {
                System.out.print("* ");
            }
            System.out.println();
        }
    }
}

Python

for row in range(1, 4):
    for col in range(1, 4):
        print("*", end=" ")
    print()

Online Working Example

C C++ Java Python

Rows Columns

Select language and click Run.

5.6 break, continue and pass

break stops a loop completely. continue skips the current iteration and moves to the next iteration. pass is used in Python as an empty placeholder statement.

Keyword	Meaning	Availability
break	Exit the loop immediately	C, C++, Java, Python
continue	Skip current loop cycle	C, C++, Java, Python
pass	Do nothing; placeholder	Python

C

for (int i = 1; i <= 5; i++) {
    if (i == 3) continue;
    if (i == 5) break;
    printf("%d\n", i);
}

C++

for (int i = 1; i <= 5; i++) {
    if (i == 3) continue;
    if (i == 5) break;
    cout << i << endl;
}

Java

for (int i = 1; i <= 5; i++) {
    if (i == 3) continue;
    if (i == 5) break;
    System.out.println(i);
}

Python

for i in range(1, 6):
    if i == 3:
        continue
    if i == 5:
        break
    print(i)

# pass example
if True:
    pass

Online Working Example

C C++ Java Python

Loop from 1 to Skip number using continue Stop loop using break at number

Select language and click Run.

5.7 Range Function

Python uses the range() function to generate a sequence of numbers. C, C++ and Java do not use range(); they use loop initialization, condition and increment.

Python range()	Meaning	Output
`range(5)`	Start from 0, stop before 5	0 1 2 3 4
`range(1, 6)`	Start from 1, stop before 6	1 2 3 4 5
`range(2, 11, 2)`	Start 2, stop before 11, step 2	2 4 6 8 10

Online Working Example

C C++ Java Python

Start Stop Step

Select language and click Run.

5.8 Loop Applications

Loops are used in applications such as total calculation, average calculation, search operations, pattern printing, menu systems and repeated input validation.

Application: Sum of Numbers

C C++ Java Python

Calculate sum from 1 to

Select language and click Run.

5.9 Practical Activities

Activity 1: Number Printing

Print numbers from 1 to 20 using for loops in all four languages.

Activity 2: Countdown

Use while loops to count down from 10 to 1.

Activity 3: Multiplication Table

Create a multiplication table program for any number.

Activity 4: Star Pattern

Use nested loops to print a rectangle pattern.

Mini Project

Create a marks processing program that asks for several marks, calculates total, average and highest mark using loops.

5.10 Interactive Final Assessment Quiz

Each correct answer gives +1 mark. Each wrong answer gives -0.5 mark. Correct answers are intentionally mixed.

1. Which loop is usually best when the number of repetitions is known?

while loop for loop pass only print loop

2. A while loop repeats while its condition is true.

True False

3. Which keyword stops a loop immediately?

continue pass break range

4. Nested loop means a loop inside another loop.

False True

5. Which keyword skips the current iteration and continues with the next one?

break stop pass continue

6. Python range(1, 6) generates numbers 1 to 5.

True False

7. Which keyword is mainly a Python placeholder that does nothing?

pass break continue return

8. Loops cannot be used to calculate totals.

True False

9. In C, C++ and Java, a common for loop includes initialization, condition and update.

False True

10. Which Python code prints 0, 1, 2?

range(1,3) range(3) range(2) range(0,2)

Your Score: 0

5.11 Module Summary

This module explained for loops, while loops, nested loops, break, continue, pass, Python range function and loop applications using C, C++, Java and Python.

Remember: Loops help programs automate repetitive processing and handle large amounts of repeated work efficiently.