Binary to decimal C program

In this post, you will learn how to convert a binary number into an equivalent decimal using the C programming language. Here, we have mentioned three ways to convert a binary to a decimal number.

A binary number consists of two numbers 0s and 1s. It is expressed in the base-2 numeral system or binary numeral system. As the computer only understands binary language that is 0 or 1, all inputs given to a computer are decoded by it into series of 0's or 1's to process it further. Any combination of 0 and 1 is a binary number such as 1011, 100, 101011, 111011 etc.

A decimal number is a base-10 number system. It ranges from 0 to 9 i.e., 0,1,2,3,4,5,6,7,8,9. Any combination of digits is a decimal number such as 61, 22, 912, 0, 5 etc. The main advantages of the decimal number system are easy-to-read, used by humans and easy to manipulate.

C convert binary to decimal using while loop

In the given C program, we ask the user to enter a number in binary number system to convert that number into decimal number system using the while loop.

#include <stdio.h>  

void main()  
{  
    // declaration of variables  
    int num, binary_num, decimal_num = 0, base = 1, rem;  
    printf("Enter a binary number: ");  
    scanf(" %d", &binary_num); 
    
    // print the binary number 
    printf("The binary number: %d \t", binary_num); 
      
    // convert binary to decimal 
    while(binary_num > 0)  
    {  
        /* divide the binary number by 10 and store the remainder in rem variable. */
        rem = binary_num % 10;   
        decimal_num = decimal_num + rem * base;  
        // divide the number with quotient  
        binary_num = binary_num / 10;
        base = base * 2;  
    }  
  
    // print the decimal
    printf("\nThe decimal number: %d \t", decimal_num); 
}  

Output of the above code:

Enter a binary number: 1101
The binary number: 1101 	
The decimal number: 13 	

Enter a binary number: 1110
The binary number: 1110 	
The decimal number: 14 

C convert binary to decimal using for loop

In the given C program, we ask the user to enter a number in binary number system to convert that number into decimal number system using the for loop.

#include <stdio.h>  

void main()  
{  
    // declaration of variables  
    int i,num, binary_num, decimal_num = 0, rem;  
    printf("Enter a binary number: ");  
    scanf(" %d", &binary_num); 
    
    // print the binary number 
    printf("The binary number: %d \t", binary_num); 
      
    // convert binary to decimal 
    for (i = 0; binary_num != 0; ++i)  
    {  
        rem = binary_num % 10;  
        binary_num = binary_num / 10;  
        decimal_num = decimal_num + (rem) * ( pow (2, i));  
          
    }  
  
    // print the decimal
    printf("\nThe decimal number: %d \t", decimal_num); 
}  

Output of the above code:

Enter a binary number: 1111
The binary number: 1111 	
The decimal number: 15 	

Enter a binary number: 11011
The binary number: 11011 	
The decimal number: 27

C convert binary to decimal using function

In the given C program, we create a custom function binaryTodecimal() to convert the user entered binary to decimal number.

#include <stdio.h>  
 
int binaryTodecimal(int bin_num);  
int main()  
{  
    // declare the local variable  
    int binary_num, dec_num;  
    printf("Enter a binary number: ");  
    scanf("%d", &binary_num);  
      
    // call the binaryTodecimal() function    
    dec_num = binaryTodecimal (binary_num); 
    printf("The decimal number: %d", dec_num);  
}  
  
// user-defined function 
int binaryTodecimal( int bin_num)  
{  
    // declaration of variables  
    int dec_num = 0, temp = 0, rem;  
    
    // convert binary to decimal 
    while (bin_num != 0)  
    {  
        rem = bin_num % 10;  
        bin_num = bin_num / 10;  
        dec_num = dec_num + rem * pow( 2, temp);  
        temp++;  
    }  
    return dec_num;  
}  

Output of the above code:

Enter a binary number: 11011
The decimal number: 27

Enter a binary number: 101011
The decimal number: 43

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