C Program to Check Power of 2

Posted in C Tutorial

Updated on Jan 11, 2024

By Mari Selvan

👁️ 88 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, efficiency and optimization are key considerations. One common optimization involves determining whether a given number is a power of 2.

Checking if a number is a power of 2 is a fundamental operation with applications in various domains.

In this tutorial, we'll explore a C program that efficiently checks whether a given number is a power of 2.

📄 Example

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

isPowerOfTwo.c

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#include <stdio.h>

// Function to check if a number is a power of 2
int isPowerOfTwo(int num) {
  // A number is a power of 2 if and only if it has a single set bit.
  // Using bitwise AND operation to check this condition.
  return (num > 0) && ((num & (num - 1)) == 0);
}

// Driver program
int main() {
  // Replace this value with your desired number
  int number = 16;

  // Check if the number is a power of 2
  if (isPowerOfTwo(number)) {
    printf("%d is a power of 2.\n", number);
  } else {
    printf("%d is not a power of 2.\n", number);
  }

  return 0;
}

💻 Testing the Program

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

Output

16 is a power of 2.

Compile and run the program to see whether the given number is a power of 2.

🧠 How the Program Works

The program defines a function isPowerOfTwo that takes an integer as input and returns 1 if the number is a power of 2 and 0 otherwise.
Inside the function, it uses a bitwise AND operation to check if the number has a single set bit, which is a characteristic of power-of-2 numbers.
The main function demonstrates the usage of the isPowerOfTwo function by checking if a given number is a power of 2.

📏 Between the Given Range

Let's dive into the C code that performs the check for powers of 2 in the range 1 to 20.

isPowerOfTwo.c

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#include <stdio.h>
#include <math.h>

// Function to check if a number is a power of 2
int isPowerOfTwo(int num) {
  return (num && !(num & (num - 1)));
}

// Driver program
int main() {
  printf("Power of 2 in the range 1 to 20:\n");

  for (int i = 1; i <= 20; ++i) {
    if (isPowerOfTwo(i)) {
      printf("%d ", i);
    }
  }

  printf("\n");

  return 0;
}

💻 Testing the Program

The output of the program, showing powers of 2 in the range from 1 to 20, will be displayed in the following format:

Output

Power of 2 in the range 1 to 20:
1 2 4 8 16

🧠 How the Program Works

The program defines a function isPowerOfTwo that checks whether a given number is a power of 2 using bitwise operations.
The main function iterates through numbers from 1 to 20 and prints those that are powers of 2.

🧐 Understanding the Concept of Power of 2

A number is considered a power of 2 if and only if it has a single set bit.

For example, 2, 4, 8, and 16 are powers of 2 because their binary representations have only one bit set.

Understanding this concept is crucial for efficient programming and algorithm design.

🎢 Optimizing the Program

The provided program is a straightforward implementation. However, there are more advanced techniques for checking if a number is a power of 2, such as using logarithmic operations or counting the number of set bits. Depending on your specific use case, you might explore these optimizations.

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