⚙️ Functions & Methods¶

Prerequisites: None

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.

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: 1. Km to Miles 2. Inches to Feet 3. 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.

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