Binary To Decimal Conversion | C Program

June 16, 2023

Binary to Decimal in C

Let’s look at Binary to Decimal in C, we will discuss the C program for binary to decimal conversion. A decimal number can be attained by multiplying every digit of binary digit with a power of 2 and adding each multiplication outcome. The power of the integer starts from 0 and counts to n-1 where n is assumed as the overall digits of integers in binary numbers.

Ex:-  (10110)2 = 
1 * 24 + 0 * 23 + 1 * 22 + 1 * 21 + 0 * 20
16 + 0 + 4 + 2 + 0 = (22)10
Program for Binary to Decimal in C

Working:-

Binary to Decimal in C

For user input num

  • Initialize i = 0, decimal = 0
  • Extract the last digit (digit = num% 10)
  • Calculate decimal equivalent of this digit
  • Add it to decimal variable
    • decimal += digit * pow(2,i);
  • Reduce the number (num /= 10
  • increment i value
While loop in C

C Program to convert Binary to Decimal Number:

Code

Run 
// C Program to convert binary to decimal
#include<stdio.h>
#include<math.h>

// function to convert binary to decimal
int convert(long long num)
{
    int i = 0, decimal= 0;
    
    //converting binary to decimal
    while (num!=0)
    {
        int digit = num % 10;
        decimal += digit * pow(2,i);

        num /= 10;
        i++;
    }
    return decimal;
}

// main program
int main()
{
    // long used rather than int to store large values
    // Ex : int wont store 111111111111 (12 digits) as
    // limit for int is 2147483647 (10 digits)
    long long binary;
    
    printf("Enter binary number: ");
    scanf("%lld", &binary);
    
    printf("%lld", convert(binary));
    
    return 0;
}

Output

Enter binary number: 101
5
While loop in C

Program to Find LCM

Program to find GCD

Program for octal to decimal conversion

Program for hexadecimal to decimal conversion

Program for decimal to binary conversion

Program for Decimal to Binary

Let us look at the program and how to convert manually the same below –

Conversion 2
conversion new

Code Decimal to Binary

Run 
#include<stdio.h>


void getBinary(int dec)
{
    // since, we may need to store large binary values using long long
    long long binary = 0;
    int rem, i = 1;
    
    while(dec != 0)
    {
        rem = dec % 2;
        dec /= 2;
        binary += rem * i;
        
        // moving to next position ex: units -> tens
        i *= 10;
    }
    printf("%lld",binary);
}
 
int main()
{
    int dec = 19;
    getBinary(dec);
    return 0;
}

Output

10011

Prime Course Trailer

Related Banners

Get PrepInsta Prime & get Access to all 200+ courses offered by PrepInsta in One Subscription

Get Prime
Software Engineering SDLC

3 comments on “Binary To Decimal Conversion | C Program”


  • edaranagarjuna36736

    #include
    #include
    int main()
    {
    int i=0.s=0,r;
    long long n;
    printf(“Enter binary number :”);
    scanf(“%lld”,&n);
    while(n>0)
    {
    r=n%10;
    s=s+r*pow(2,i);
    n=n/10;
    i++;
    }
    printf(“Decimal number : %lld”,s);
    }


  • Sushil

    There is one mistake in Binary to Decimal
    the last Printf statement in the main() should be either typecasted or instead of putting %lld you should put %d otherwise you’re getting a garbage value as a Decimal…..
    so replace last print from main() by
    printf(“Decimal is : %lld”,(long long)convert(binary)); //Typecasted int into long long
    OR
    printf(“%d”, convert(binary));


  • Sanket

    there is no invalid state for invalid binary number
    #include

    int main()
    {
    int num, binary_val, decimal_val = 0, base = 1, rem,flag=0;

    printf(“Insert a binary num (1s and 0s) \n”);
    scanf(“%d”, &num); /* maximum five digits */

    binary_val = num;
    while (num > 0)
    {

    rem = num % 10;
    if (rem==1 || rem==0)
    {
    decimal_val = decimal_val + rem * base;
    //num/=10;
    num = num / 10 ;
    //base*=2;
    base = base * 2;
    }
    else
    {
    printf(“Invalid number”);
    flag=1;
    break;
    }

    }
    if(flag==0)
    {
    //display binary number
    printf(“The Binary num is = %d \n”, binary_val);
    //display decimal number
    printf(“Its decimal equivalent is = %d \n”, decimal_val);
    return 0;
    }
    }