Can someone explain this ???

[Rob Hopping]

I've set convertionValue equal to (binaryString.charAt(0)) but when I print them out I get two different answers.

The following produces:

13
3
51

Why is it addind 48 to convertionValue?


// main line of program
public static void main (String[] args) {

String binaryString = ("3677895775421");
int convertionValue;

convertionValue = (binaryString.charAt(0));

System.out.println(binaryString.length());
System.out.println(binaryString.charAt(0));
System.out.println(convertionValue);
}
}

[Dun Dagda]

That is because charAt will return the ASCII code of the character at that position in the String. The ASCII code of the character 0 (zero) is 48, character 1 is ASCII 49, etc.
So to convert the character code for the character "1" to its numerical equivalent, you need to subtract 48 from the character code.

DD

[marc weber]

See http://www.asciitable.com/

[Dun Dagda]

Here's something that might help you out.

  
public class BinaryToDecimal {
    
    public static void main(String[] args) {
        String binaryString = "11010011";
        int character = 0;
        int binaryPosition = 1;
        int decimalTotal = 0;
        for (int loop = (binaryString.length() - 1); loop >= 0; loop--) {
            character = (binaryString.charAt(loop)) - 48;
            decimalTotal += character * binaryPosition;
            binaryPosition *= 2;
        }
        System.out.println("Decimal equivalent of " + binaryString + 
                           " is " + decimalTotal);
    }
}
 

Try pasting this into a .java file and compiling and running it yourself.

DD