C Exercises: Convert a binary number into a decimal using math function

Last update on July 31 2025 05:46:34 (UTC/GMT +8 hours)

46. Binary to Decimal Using Math Function

Write a C program to convert a binary number into a decimal number using the math function.

The task is to write a C program that converts a binary number into its decimal equivalent using mathematical functions. This involves processing each digit of the binary number and applying the appropriate power of 2 to calculate the decimal value.

Visual Presentation:

Convert a binary number into a decimal using math function

Sample Solution:

C Code:

#include <stdio.h> // Include the standard input/output header file.
#include <math.h>  // Include the math functions header file.

void main()
{
    int n1, n; // Declare variables to store input and results.
    int dec = 0, i = 0, j, d; // Initialize variables for decimal conversion.

    printf("\n\nConvert Binary to Decimal:\n "); // Print a message.
    printf("-------------------------\n"); // Print a separator.

    printf("Input the binary number:"); // Prompt the user for input.
    scanf("%d", &n); // Read the binary number from the user.
    n1 = n; // Store the original binary number for display.

    // Loop to convert binary to decimal.
    while (n != 0)
    {  
        d = n % 10; // Get the rightmost digit of the binary number.
        dec = dec + d * pow(2, i); // Convert and accumulate the decimal value.
        n = n / 10; // Remove the rightmost digit from the binary number.
        i++; // Increment the position counter.
    }

    // Print the result.
    printf("\nThe Binary Number: %d\nThe equivalent Decimal Number is: %d\n\n", n1, dec);
}

Output:

Convert Binary to Decimal:                                                                                    
 -------------------------                                                                                    
Input  the binary number :1010100                                                                             
                                                                                                              
The Binary Number : 1010100                                                                                   
The equivalent Decimal  Number is : 84

Flowchart:

For more Practice: Solve these Related Problems:

Write a C program to convert a binary number to decimal using the pow() function for exponentiation.
Write a C program to convert a binary string to decimal using math functions and recursion instead of loops.
Write a C program to convert a binary number to decimal by calculating the number of digits using logarithmic functions.
Write a C program to convert a binary number to decimal and then validate the result by converting it back.

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