如何使用模数在Java中将二进制转换为十进制？

Question

I'm trying to write a code that will allow the user to input a number in binary (with a limit of 8 digits) using modulus. I have this so far:

import java.util.Scanner; public class Main {

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    System.out.println("Enter a Binary Number (8 digit limit)");
    int binaryNum = input.nextInt();
    int m = 0;
    int l;
    for (int n = 0; n <= 7; n++){
        l = (2^n);
        if(binaryNum%(10^(n+1)) == (10^n)){
            m = m + l;
            binaryNum = binaryNum - (10^n);
        }
    }
    System.out.println("Decimal: " + m);
}

}

I tried inputting the number 1001010, but whenever I did, it came out as "Decimal: 2" which is clearly wrong. Can someone help?

Answer 1

import java.util.Scanner; 

public class Main {

public static void main(String[] args) {

    Scanner input = new Scanner(System.in);

    System.out.println("Enter a Binary Number (8 digit limit)");

    int binaryNum = input.nextInt(); // reading binary number

    int m = 0; // to store decimal number

    int l = 0; // to manage power of 2
    int d = 0; // to store intermediate result

    while (binaryNum != 0){ // looping till all digits are over

        d = binaryNum % 10; // taking the last bit of the binary number

        d *= Math.pow(2, l++); // finding 2^l 

        binaryNum /= 10; // dividing the binary number by 10 to shift one bit

        m += d; // add the result to decimal 
    }

    System.out.println("Decimal: " + m); // display result
}
}

I have edited the code so that the binaryNum is converted in to decimal properly. Hope this helps.!!

Answer 2

You can use Integer.parseInt to convert a string into an integer, if you do it using a base 2:

int decimalValue = Integer.parseInt(c, 2);

You should be able to get the binary value for it.

Example:

System.out.println(Integer.parseInt("1001010", 2));

Output: 74

All you need need to implement now is the restriction for the length of the string the user can, which you want to be 8, and you are good to go.

If you don't want to use the parseInt you can also do:

        int binaryNumber = 10201; //example input binary
         int decimal = 0;
            int p = 0;
            while(true){
              if(binaryNumber == 0){
                break;
              } else {
                  int temp = binaryNumber%10;
                  decimal += temp*Math.pow(2, p);
                  binaryNumber = binaryNumber/10;
                  p++;
               }
            }
        System.out.println(decimal);

In this case I am converting from an int , which I guess will be ok for you, you just need to accept an int on the Scanner instead of a String , or convert the String to an int and this will do what you need, I think you misused some of the operations on your implementation.