# Thread: Converting a 2's complement to the proper integer

1. Member
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Sep 2011
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## Converting a 2's complement to the proper integer

So my question accepts an input as an 8 char string that is a 2s complement of an integer, and then prints the right integer out. I cannot use any classes that do the conversion but i can use any I/O facilities.

Now i am still new to Java terms and not very knowledgeable of terms yet, so what does it mean that i can use any I/O facilities.

Back to what i am thinking of doing

I accept the string lets say, 000000C2 which is 194, (c = 12) 12 x 16^1 + 2*16(0) == 192 + 2 = 194

I send my string to
Java Code:
```public String toBinary (String s){
String ret = "";
while (s.length () != 0){
if(s.charAt (0) == '0'){
ret = ret + "0000";
}```
Which will convert 0 - F to its 4 binary part. Then returns the 32 bit binary code.
Now if it positive i can just go through right to left if the value is 1 i add 16^i to an int, and i increases every time i loop through a value.
If negative i have to twos complement - convert 1s to 0s, 0s to 1s and i subtract one because im going from twos complement back to its original.

2. Member
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May 2011
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## Re: Converting a 2's complement to the proper integer

Try this,

System.out.println(Integer.parseInt("000000C2",16) );

Regards,
Jing-yi

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