C++ Program to find Number Combination

Posted in C++ Tutorial

Updated on Oct 27, 2024

By Mari Selvan

👁️ 115 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, creating combinations of numbers is a common and useful task. A combination is a selection of items from a collection, where the order of selection does not matter.

In this tutorial, we'll explore a C++ program that efficiently generates combinations of two specified numbers within a given range.

📄 Example

Let's take a look at the C++ code that achieves this functionality.

generateCombinations.cpp

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#include <iostream>

// Function to calculate the number of digits in a number
int countDigits(int num) {
  int count = 0;
  while (num != 0) {
    num /= 10;
    ++count;
  }
  return count;
}

// Function to generate combinations of two numbers up to a specified limit
void generateCombinations(int number1, int number2, int limit) {
  std::cout << "List of combinations of " << number1 << " and " << number2 << " up to " << limit << ":\n";

  for (int i = 1; i <= limit; ++i) {
    int currentNumber = i;

    // Check if the current number contains only the specified digits
    while (currentNumber > 0) {
      int digit = currentNumber % 10;
      if (digit != number1 && digit != number2) {
        break;
      }
      currentNumber /= 10;
    }

    // If the current number contains only the specified digits, print it
    if (currentNumber == 0) {
      std::cout << i << " ";
    }
  }

  std::cout << "\n";
}

// Driver program
int main() {
  // Replace these values with your desired numbers and limit
  int targetNumber1 = 4;
  int targetNumber2 = 8;
  int combinationLimit = 500;

  // Call the function to generate combinations
  generateCombinations(targetNumber1, targetNumber2, combinationLimit);

  return 0;
}

💻 Testing the Program

To test the program with different values, replace the values of targetNumber1, targetNumber2, and combinationLimit in the main function.

Output

List of combinations of 4 and 8 up to 500:
4 8 44 48 84 88 444 448 484 488

Compile and run the program to see the list of combinations.

🧠 How the Program Works

The program defines a function countDigits to calculate the number of digits in a given number.
The function generateCombinations generates combinations of two specified numbers up to a given limit.
Inside the function, it iterates through numbers from 1 to the specified limit.
For each iteration, it checks if the current number contains only the specified digits.
If the condition is met, the current number is a combination, and it is printed.

🧐 Understanding the Concept of Number Combination

Before delving into the code, let's take a moment to understand the concept of combinations. In mathematics, a combination is a selection of items from a collection, where the order of selection does not matter.

For example, consider the specified numbers as 4 and 8. The combinations of 4 and 8 up to 500 include 4, 8, 44, 48, 84, 88, 444, 448, 484, and 488.