Java character array to binary string

Question

Consider the following character array

char[] u = {'a', 'b', 'b', 'a' };

I am looking for the most time efficient way in to convert it to a binary string (of the kind 0110) since I need to do some bit shifting and counts on the array in an efficient manner. The array above would be translated to an integer value 6, binary 0110.

I've used a converting to a new string, and then do two replace calls on it, before converting it to an integer with radix 2 but it doesn't look like an efficient way to me.

Any help?

How do you know 00000001 is just {'b'} and not {'a'a'a'a'a'b} — arynaq
– arynaq, Commented Mar 21, 2014 at 14:50
Cause I know the length of the original char array,as U Mad said. — Lincoln
– Lincoln, Commented Mar 21, 2014 at 18:18

RokL · Accepted Answer · 2014-03-21 14:43:33Z

1

int num = 0;
for(char c : u) {
    num = (num << 1) + (c - 'a');
}

This should work.

answered Mar 21, 2014 at 14:43

RokL

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Comments

eivour · Accepted Answer · 2014-03-21 14:51:03Z

1

How about this?

int output=0;
for(int i=0;i<u.length();i++)
    output=output<<1|u[i]-'a';

edited Mar 21, 2014 at 14:51

answered Mar 21, 2014 at 14:44

eivour

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2 Comments

RokL Over a year ago

This wouldn't compile as u is a char array, not a string. If it was a string it still wouldn't compile since the correct method is charAt not getCharAt.

eivour Over a year ago

Oh I'm sorry, I forgot that. Just replace u.getCharAt(i) for u[i].

test27 · Accepted Answer · 2014-03-21 14:52:56Z

0

try this

char[] u = {'a', 'b', 'b', 'a' };
 for(int i=0;i<u.length;i++){
  int y = (int)u[i];
  System.out.println(Integer.toBinaryString(y));}

hope it helps

answered Mar 21, 2014 at 14:52

test27

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