C++ Program to Check Power of 3

Posted in C++ Tutorial

Updated on Jan 11, 2024

By Mari Selvan

👁️ 62 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, one often encounters the need to check if a given number is a power of another.

In this case, we'll explore a C++ program specifically designed to check if a number is a power of 3.

The logic behind this program involves repeatedly dividing the number by 3 until it becomes 1, indicating that it is a power of 3.

📄 Example

Let's delve into the C++ code that achieves this functionality.

isPowerOf3.cpp

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#include <iostream>

// Function to check if a number is a power of 3
bool isPowerOf3(int n) {
  // Keep dividing the number by 3 until it is greater than 1
  while (n % 3 == 0 && n > 1) {
    n /= 3;
  }

  // If the final value is 1, the original number is a power of 3
  return n == 1;
}

// Driver program
int main() {
  // Replace this value with your desired number
  int number = 27;

  // Check if the number is a power of 3
  if (isPowerOf3(number)) {
    std::cout << number << " is a power of 3" << std::endl;
  } else {
    std::cout << number << " is not a power of 3" << std::endl;
  }

  return 0;
}

💻 Testing the Program

To test the program with different numbers, simply replace the value of number in the main function.

Output

27 is a power of 3

Compile and run the program to see if the given number is a power of 3.

🧠 How the Program Works

The program defines a function isPowerOf3 that takes an integer as input and checks if it is a power of 3.
Inside the function, it repeatedly divides the number by 3 until it becomes greater than 1.
If the final value is 1, the original number is a power of 3, and the function returns true; otherwise, it returns false.
The driver program in the main function tests a specific number and prints whether it is a power of 3 or not.

📏 Between the Given Range

Let's take a look at the C++ code that checks for powers of 3 in the given range.

isPowerOfThree.cpp

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#include <iostream>

#include <cmath>

// Function to check if a number is a power of 3
bool isPowerOfThree(int num) {
  if (num <= 0) {
    return false;
  }

  // Using logarithmic property to check if num is a power of 3
  double logResult = log10(num) / log10(3);
  return (logResult - int(logResult)) == 0;
}

// Driver program
int main() {
  // Output header
  std::cout << "Power of 3 in the range 1 to 20:" << std::endl;

  // Loop through numbers 1 to 20 and check if they are powers of 3
  for (int i = 1; i <= 20; ++i) {
    if (isPowerOfThree(i)) {
      std::cout << i << " ";
    }
  }

  std::cout << std::endl;

  return 0;
}

💻 Testing the Program

Output

Power of 3 in the range 1 to 20:
1 3 9

Compile and run the program to see the numbers in the range 1 to 20 that are powers of 3.

🧠 How the Program Works

The program defines a function isPowerOfThree that checks if a given number is a power of 3.
Inside the function, it uses logarithmic properties to determine if the logarithm of the number with base 3 is an integer.
The main function tests this by iterating through numbers from 1 to 20 and printing those that are powers of 3.

🧐 Understanding the Concept of Power of 3

Before diving into the code, let's understand the concept of a power of 3.

A number is considered a power of 3 if it can be expressed as 3^n, where n is an integer.

For example, 1, 3, 9, 27, and so on are powers of 3.

🎢 Optimizing the Program

While the provided program is straightforward, there are alternative approaches to check if a number is a power of 3. Consider exploring other mathematical techniques for optimization.

Feel free to incorporate and modify this code as needed for your specific use case. Happy coding!