Jason arora Jason arora - 4 months ago 14
Java Question

How to convert ones' complement number into its 2's complement?


Given:A binary number in the form of String.Convert this into its 2's complement form


Example:

Input:

00000101

Output:

11111011

I know how to convert a binary number into its 1's compliment form. But I am unable to convert into 2 complement form.

For Example:

GivenString :111

1s Compliment 000

How to code1: Adding '1' to the 1's complement and 1+1=1?

MyCodeFor 1s Compliment:

public static String complimentDecimal(String strnew)

{


//Replace the 0s with 1s and 1s with 0s
StringBuilder sb = new StringBuilder();
for(int j=0;j<strnew.length();j++)
{
if(strnew.charAt(j)=='0')
sb.append("1");
else if(strnew.charAt(j)=='1')
sb.append("0");
}
String s1 = sb.toString();

}

Answer

Convert the one's compliment to decimal form using Integer.parseInt(<String value>, 2)
You will get decimal form of the binary number. Add one to it and convert the number back to binary.

public static String complimentDecimal(String strnew)
{
    int s2=Integer.parseInt(strnew,2);
    if (s2==0)
    {
        String s4="1";
        for(int j=0;j<strnew.length();j++)
        {
            s4+="0";
        }
        return s4;
    }
    else{
        StringBuilder sb = new StringBuilder();
          for(int j=0;j<strnew.length();j++)
          {
              if(strnew.charAt(j)=='0') 
                  sb.append("1");
              else if(strnew.charAt(j)=='1') 
                  sb.append("0");
          }
          String s1 = sb.toString();
          int s = Integer.parseInt(s1, 2);//parse int radix = 2 for binary
          s++; //increment by one
        return Integer.toBinaryString(s);
    }
}

This will work for zero's.

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