Binary to Decimal & Decimal to Binary Bitwise Right-shift Operator
The Java code has two number conversion operations; one is decimal to binary conversion and second binary to decimal conversion. These two operations are done by bitwise right shift operator.
Conditional switch selects the case, one of the two conversion operation is to carry out from choice input given to program. If choice is 1, switch selects case1 (binary to decimal conversion) and if choice is 2, switch selects case2 (decimal to binary conversion).
Output
Output 2
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Conditional switch selects the case, one of the two conversion operation is to carry out from choice input given to program. If choice is 1, switch selects case1 (binary to decimal conversion) and if choice is 2, switch selects case2 (decimal to binary conversion).
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| Decimal 2 Binary by Right shift |
Binary to decimal conversion
Assume that, choice is 1 and switch selects binary to decimal conversion operation. The user is prompted enter 8 binary bits as input which is to be converted into a decimal value.
Assume that, binary input given is 011000000 and it is stored into a string object “bstr” and initialize decval = 0.
Bstr =”[01100000]” characters indexed (0,1,2,.) from left to right
decval =0;
the iteration variable n start from 8-1 to 0 for rightshift operator,>>.
If bstr[n] == 1 ; check bstr[n] ==’1’ if true , do binary OR operation with decval |128,
iteration n=7
decval = decval>>1; decval rightshift by 1 (move 1 bit toward right) ( result decval=0)
if bstr[7] == ‘1’ ; condition is false , move to next iteration
iteration n=6
decval = decval >>1; decval rightshift by 1 ( result decval=0)
if bstr[6] == ‘1’ ; condition is false , move to next iteration move next iteration
The string bstr has none bits is one index from 7 to 3 (reverse order) and condition becomes false from iteration n=7 to 3, therefore no chance for OR operation.
Iteration n=2
decval = decval >>1; decval rightshift by 1 ( result decval=0)
if bstr[2] == ‘1’ ; condition is true , do binary OR operation with decval |128,
decval = decval |128;
move to next iteration
Iteration n=1
decval = decval >>1; decval rightshift by 1 ( result decval=64)
if bstr[1] == ‘1’ ; condition is true , do binary OR operation with decval |128,
decval = decval |128;
move to next iteration
Iteration n=0
decval = decval >>1; decval rightshift by 1 ( result decval=96)
if bstr[0] == ‘1’ ; condition is false,
move to next iteration and loop end.
Finally the result decval =96
Decimal to Binary Conversion
Assume that, choice is 2 and switch selects decimal to binary conversion operation. The user is prompted enter decimal value between [0 - 255] as input, which is to be converted into 8 bit binary.
Assume that, binary input given is 143 and it is stored into decval and a stringbuffer object “bstr” initialized empty constructor.
Bstr =”” empty string
decval =143;
char c = ( decval & 1 ) ==1 ? ‘1’ : ‘0’
set char c= ‘1’ or ‘0’ by doing binary AND operation decval & 1 and result compared with 1 if it is true, c=’1’ otherwise c=’0’.
iteration n=0
(decval & 1) == 1 ? ‘1’ :’0’ condition is true, char c set ‘1’
bstr.insert(c,0) ; insert c=’1’ into bstr at index 0
decval =decval >> 1 ; decval right shift by 1 bit and result decval =71
iteration n=1
(decval & 1) == 1 ? ‘1’ :’0’ condition is true, char c set ‘1’
bstr.insert(c,0) ; append c=’1’ into bstr at index 0
decval =decval >> 1 ; decval right shift by 1 bit and result decval =35
iteration n=2
(decval & 1) == 1 ? ‘1’ :’0’ condition is true, char c set ‘1’
bstr.insert(c,0) ; append c=’1’ into bstr at index 0
decval =decval >> 1 ; decval right shift by 1 bit and result decval =17
The same process iterated until n< 8. The stringbuffer object bstr contains results of 8 bits binary.
bstr =”10001111”
import java.util.Scanner;
public class RightShiftOpr
{
public final static int nbits=8;
public static String dec2bin(int decval)
{
StringBuffer bufstr = new StringBuffer();
for(int n=0;n<RightShiftOpr.nbits;n++)
{
char c=( (decval & 1) == 1) ? '1' : '0';
bufstr.insert(0, c);
decval >>=1;
}
return bufstr.toString();
}
public static int bin2dec(String bstr)
{
int decval=0;
for(int n=RightShiftOpr.nbits-1;n>=0;n--)
{
decval >>= 1;
if ( bstr.charAt(n) == '1' )
decval = decval | 128;
}
return decval;
}
public static void main(String[] args)
{
Scanner sc=new Scanner(System.in);
int decval=0; String bstr="";
System.out.println("nt Decimal to Binary using >>
RightShift Operator");
System.out.println("n Select Choice nt 1 - Binary2Dec
2- Dec2Binary ");
int choice =sc.nextInt();
switch ( choice ) {
case 1:
System.out.println("Enter 8 bit Binary numbers");
bstr= sc.next();
decval = RightShiftOpr.bin2dec(bstr);
System.out.println("nDecimal value :" + decval);
break;
case 2:
System.out.println("Enter Decimal number range [0 - 255]");
decval = sc.nextInt();
bstr = RightShiftOpr.dec2bin(decval);
System.out.println("nBinary bits :" + bstr);
break;
}
sc.close();
}
}
Output
Positive Integer to Binary using >>RightShift Operator Select Choice 1 - Binary2Dec 2- Dec2Binary 1 Enter 8 bit Binary numbers 10001111 Decimal value :143
Output 2
Positive Integer to Binary using >> RightShift Operator Select Choice 1 - Binary2Dec 2- Dec2Binary 2 Enter Decimal number range [0 - 255] 19 Binary bits :00010011
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