How to do it…

To convert a binary number into a decimal, perform the following steps:

1. Enter a binary number.
2. Apply a mod 10 (% 10) operator to the binary digits of the binary number to isolate the last bit of the binary number.
3. Left-shift the binary digit isolated in step 2 to multiply it by the power of 2. 
4. Add the product of the previous multiplication to the variable that will store the result, that is, the decimal number. Let's call the variable dec.
5. The last digit of the binary number is truncated.
6. Repeat step 2 to step 4 until all the bits of the binary digits are over.
7. Display the decimal in the dec variable.

The program for converting a binary number into a decimal is as follows:

binintodec.c
#include <stdio.h>
void main()
{
    int num,bin,temp,dec=0,topower=0;
    
    printf("Enter the binary number: ");
    scanf("%d",&bin);
    temp=bin;
    while(bin >0)
    {
        num=bin %10;
        num=num<<topower;
        dec=dec+num;
        topower++;
        bin=bin/10;
    }    
    printf("The decimal of %d is %d\n",temp,dec);
}

Now, let's go behind the scenes to understand the code better.