Thread: want to modify code that converts binary code to decimal numbers

The code here I have works fine if I just want to ask the user to enter four digits:

//java application that asks user to input  binary numbers(1 or 0) and convert them  to decimal numbers
 
import java.util.Scanner; //program uses class scanner
 
public class binarynumber{
 
	//main method that executes the java application
 
	public static void main(String args[]){
 
		//declares variables
 
		int digit;
		int base=2;
        int degree;
        double decimal;
        int binary_zero=0;
        int binary_one=1;
        //create scanner for object input
 
        Scanner input=new Scanner(System.in);
 
        System.out.println("Input a digit for a binary number(1 or 0):"); //prompt user to input a binary number
        digit=input.nextInt();
 
       if(digit==1 || digit==0)
           System.out.printf("binary in discimal form is %f",digit*(Math.pow(base,0)));
           double ones_place=digit*Math.pow(base,0);
 
       System.out.println("Input a digit for a binary number(1 or 0):"); //prompt user to input a binary number
        digit=input.nextInt();
          if(digit==1 || digit==0)
             System.out.printf("binary in decimal form is %f", digit*(Math.pow(base,1)));
             double tens_place=digit*Math.pow(base,1);
         System.out.println("Input a digit for a binary number(1 or 0):"); //prompt user to input a binary number
               digit=input.nextInt();
 
         if(digit==1 || digit==0)
            System.out.printf("binary in decimal form is %f",digit*(Math.pow(base,2)));
            double hundreds_place=digit*Math.pow(base,2);
 
         System.out.println("Input a digit for a binary number(1 or 0):"); //prompt user to input a binary number
        digit=input.nextInt();
 
           if(digit==1 || digit==0)
              System.out.printf("binary in decimal form is %f", digit*(Math.pow(base,3)));
 
             double thousands_place=digit*Math.pow(base,3);
 
 
        System.out.printf( "Output in decimal form is %f", ones_place+tens_place+hundreds_place+thousands_place);
 
 
 
 
 
 
 
 
 
 
	}//end main
 
}//end class

here is the output of my code when I run the java application:

Input a digit for a binary number(1 or 0):
1
binary in discimal form is 1.000000Input a digit for a binary number(1 or 0):
0
binary in decimal form is 0.000000Input a digit for a binary number(1 or 0):
0
binary in decimal form is 0.000000Input a digit for a binary number(1 or 0):
1
binary in decimal form is 8.000000Output in decimal form is 9.000000Press any ke
y to continue . . .

The thing is, I want the java application to input more than four digits for the user and I want it to loop it manytimes f until the user ask it to stop. What should I do?

Originally Posted by GregBrannon

Put the necessary code in a loop, usually a do/while() or while() loop, that repeats until the user indicates the input is complete or the correct number and correct data has been retrieved.

I rewrote my code to incorporate a while loop:

 
//java application that asks user to input any binary numbers(1 or 0) and convert them  to decimal numbers
 
import java.util.Scanner; //program uses class scanner
 
public class binarynumber{
 
	//main method that executes the java application
 
	public static void main(String args[]){
 
		//declares and initialized  variables
 
		int digit=1;
		double base=2;
        int degree=0;
        double total=0;
        double decimal=digit*Math.pow(base,degree); //formula that converts binary digits to decimal numbers
 
 
        Scanner input=new Scanner(System.in);
System.out.println("Enter a binary digit(one or zero)"); //prompts user for an input
        digit=input.nextInt(); //reads user from input
 
       System.out.printf("Conversion for decimal format is %f",decimal);
 
 
//while loop continues until user inputs integers that are not 1 or not zero
        while(digit!=1 || digit!=0){
 
			System.out.println("Enter a binary digit(one or zero)");
			digit=input.nextInt();
			decimal=digit*Math.pow(base,degree);
			degree++;
			System.out.printf("Conversion for decimal format is %f",decimal); //displays decimal result each time
			total=total+decimal;// sums up the total number of binary numbers that the user input that have been converted over to decimal numbers
 
		}
 
if(digit!=0 || digit!=1)
		   System.out.printf("the binary digit %f", total); //displays total number of binary numbers that have been converted to decimal numbers after the user exits the while loop
 
 
 
 
	   }//end main
 
   }//end class

Here is the output of my code when I execute the code:

Enter a binary digit(one or zero)
1
Conversion for decimal format is 1.000000Enter a binary digit(one or zero)
1
Conversion for decimal format is 1.000000Enter a binary digit(one or zero)

1
Conversion for decimal format is 2.000000Enter a binary digit(one or zero)
1
Conversion for decimal format is 4.000000Enter a binary digit(one or zero)
1
Conversion for decimal format is 8.000000Enter a binary digit(one or zero)
0
Conversion for decimal format is 0.000000Enter a binary digit(one or zero)

The problem is, when I input a number that isn't 1 or one, it won't exit the while loop and displayed the total like I want it to. What am I doing wrong?

while(digits!=-1 || digit!=0){

You need to think about how the OR operator (||) works. If either of the sub conditions are true, then the whole condition is true. With the AND operator (&&) all sub conditions must be true for the whole condition to be true.

What if digits == 0? Then digits !=1 is true and the whole condition returns true.

couldn't I just used the while loop

I was talking about the boolean expression inside the ()s that's part of the while statement.
What I said would also be true of the condition expression used in an if statement or anywhere else a boolean condition is used.

I haven't learned boolean yet.

You're using boolean expressions in the while statement and if statements.
X == 2 is a boolean expression. It resolves to a boolean value of true or false.
((x == 2) && (y > 3)) is (what I call) a compound boolean expression: two simple expressions joined by a boolean operator like AND or OR. again it resolves to a boolean value

Couldn't I just incorporate teh while loop without any if statements

I don't know what if statement you are referring to. What would be its purpose?