C++ Exercises: Check if a given integer is a power of three or not

Last update on April 12 2025 12:58:35 (UTC/GMT +8 hours)

12. Check if Integer is a Power of Three

Write a C++ program to check if a given integer is a power of three or not.

Input: 9
Output: true
Input: 81
Output: true
Input: 45
Output: false

Sample Solution:

C++ Code :

#include <iostream>
using namespace std;

// Function to check if a number is a power of three
string is_PowerOf_Three(int n) {
    // Continuously divide 'n' by 3 until it's not divisible by 3
    while (n % 3 == 0) {
        n = n / 3;
    }

    // If the final value of 'n' is 1, then it is a power of three
    if (1 == n) {
        return "True";
    } else {
        return "False"; // Otherwise, it is not a power of three
    }
}

int main(void) {
    // Test cases to check if the numbers are powers of three
    int n = 15;
    cout << "\nIf " << n << " is power of three? " << is_PowerOf_Three(n) << endl;

    n = 9;
    cout << "\nIf " << n << " is power of three? " << is_PowerOf_Three(n) << endl;

    n = 243;
	cout << "\nIf " << n << " is power of three? " << is_PowerOf_Three(n) << endl;

    return 0; // Return 0 to indicate successful completion
}

Sample Output:

If 15 is power of three? False

If 9 is power of three? True

If 243 is power of three? True

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program to determine if a given integer is a power of three by using a recursive function.
• Write a C++ program that reads a number and checks for power-of-three property by continuously dividing by 3 until reaching 1.
• Write a C++ program to check if a number is a power of three using logarithms and integer rounding for verification.
• Write a C++ program that implements a loop-based approach to verify if an integer is a power of three without using the division operator directly.

C++ Code Editor:

Click to Open Editor

Contribute your code and comments through Disqus.

Previous: Write a C++ programming to add repeatedly all digits of a given non-negative number until the result has only one digit.
Next: For a non negative integer in the range 0 ≤ i ≤ n write a C++ programming to calculate the number of 1's in their binary representation and return them as an array.