⚙️ 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.

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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