⚙️ Functions & Methods
Functions (or methods) are the building blocks of reusable code. These problems focus on defining logic once and calling it multiple times with different parameters.
Examples
1. Simple Greeting Function
Rating: Beginner | Difficulty: Easy Write a function that takes a name as a string and prints "Hello, [Name]!".
💡 Hint
Define a function with one parameter and no return value (void in C/Java).
2. Max of Two (Function)
Rating: Beginner | Difficulty: Easy
Create a function findMax(a, b) that returns the larger of two numbers.
💡 Hint
The function should have an integer return type.
3. Factorial Function
Rating: Beginner | Difficulty: Easy
Write a function factorial(n) that returns the factorial of a given number.
💡 Hint
Reuse the loop logic from the Loops section, but wrap it in a function.
4. Prime Checker Function
Rating: Intermediate | Difficulty: Medium
Create a boolean function isPrime(n) that returns true if a number is prime and false
otherwise.
💡 Hint
Useful for many advanced problems! Return 1/0 in C
or true/false in Java/C++.
5. Circle Properties
Rating: Beginner | Difficulty: Easy
Write functions to calculate the area and circumference of a circle given its radius.
💡 Hint
Area = 3.14 * r * r, Circumference = 2 * 3.14 * r.
6. Power Function
Rating: Intermediate | Difficulty: Medium
Write a function power(base, exponent) that calculates the power of a number without using math
libraries.
💡 Hint
Use a loop to multiply the base exponent times.
7. Array Sum Function
Rating: Intermediate | Difficulty: Medium Write a function that takes an array and its size as parameters and returns the sum of all elements.
💡 Hint
In C, you must pass the size separately. In Java, you can use
arr.length.
8. Even/Odd Logic
Rating: Beginner | Difficulty: Easy
Write a function isEven(n) that returns true if n is even. Use this function in your main
program to print all even numbers between 1 and 50.
💡 Hint
Call the
function inside a loop in main.
9. Fibonacci Term Finder
Rating: Intermediate | Difficulty: Medium
Write a function getFibonacci(n) that returns the Nth term of the Fibonacci sequence.
💡 Hint
If n=5, return 3 (Sequence: 0, 1, 1, 2, 3).
10. Swap by Reference
Rating: Advanced | Difficulty: Medium
Write a function to swap two numbers. Challenge: Ensure the values stay swapped in the calling
function (main).
💡 Hint
Use pointers in C or pass-by-reference in C++. In Java, you'll need to use an array or an object since primitives are pass-by-value.
11. String Length Function
Rating: Intermediate | Difficulty: Medium
Re-implement the strlen or .length() logic inside a custom function.
💡 Hint
Pass the string to the function and loop until the null terminator.
12. GCD and LCM
Rating: Advanced | Difficulty: Medium
Write two functions: findGCD(a, b) and findLCM(a, b). Use the formula LCM = (a*b)/GCD.
💡 Hint
The Euclidean algorithm is the most efficient way to find GCD.
13. Unit Converter Utility
Rating: Intermediate | Difficulty: Medium Create a menu-driven program using functions to convert:
- Km to Miles
- Inches to Feet
- Celsius to Fahrenheit
💡 Hint
Use a switch case in main to call different functions.
14. Array Average and Grade
Rating: Intermediate | Difficulty: Medium Write one function to find the average of an array of marks, and another to return the grade based on that average.
💡 Hint
Chain the functions:
getGrade(getAverage(marks)).
15. Perfect Number Finder
Rating: Pro | Difficulty: Hard
Write a function isPerfect(n). Use this function to find and print all perfect numbers between 1
and 10,000.
💡 Hint
Perfect numbers are rare (6, 28, 496...). Your loop
in main will call the function 10,000 times.