C++ Exercises: Convert a decimal number to binary number

Last update on April 07 2025 13:01:06 (UTC/GMT +8 hours)

70. Decimal to Binary Conversion

Write a program in C++ to convert a decimal number to a binary number.

Visual Presentation:

Sample Solution:-

C++ Code :

#include <iostream> // Include input/output stream library
#include <math.h> // Include math library for mathematical functions
using namespace std; // Use the standard namespace

int main() // Main function where the execution of the program starts
{
    int dec_num, rem, quot, i = 1, j; // Declare integer variables 'dec_num', 'rem', 'quot', 'i', 'j' and initialize 'i' as 1
    int bin_num[100]; // Declare an integer array 'bin_num' of size 100 to store binary digits

    cout << "\n\n Convert a decimal number to binary number:\n"; // Display message prompting for decimal to binary conversion
    cout << "---------------------------------------------------\n"; // Display separator line
    cout << " Input a decimal number: "; // Prompt user to input a decimal number
    cin >> dec_num; // Read the decimal number input by the user

    quot = dec_num; // Assign the decimal number to 'quot' initially
    while (quot != 0) { // Loop to convert decimal number to binary
        bin_num[i++] = quot % 2; // Store remainder of division by 2 (binary digit) in 'bin_num' array and increment 'i'
        quot = quot / 2; // Update 'quot' by dividing it by 2 (binary conversion process)
    }

    cout << " The binary number is: "; // Display message indicating the binary number output
    for (j = i - 1; j > 0; j--) { // Loop to display the binary number stored in 'bin_num' array in reverse order
        cout << bin_num[j]; // Output each binary digit from 'bin_num' array
    }
    cout << "\n"; // Move to the next line after displaying the binary number
}

Sample Output:

 Convert a decimal number to binary number:                            
---------------------------------------------------                    
 Input a decimal number: 35                                            
 The binary number is: 100011

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program to convert a decimal number to its binary representation using iterative division by 2.
• Write a C++ program that reads a decimal integer and outputs the corresponding binary number as a string.
• Write a C++ program to compute the binary equivalent of a decimal number using recursion and print the result.
• Write a C++ program that converts a decimal number to binary by repeatedly taking remainders and assembling the result in reverse order.

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