Sharon writes:
>
> What does this mean? What is 0xf?
>
> char c;
> c = (char) ((x >> 4) & 0xf);
>
>
> -Sharon
>
char c; - means to declare variable 'c' of type 'char' (usually
means an 8-bit wide variable)
x >> 4 - means to shift the variable 'x' to the right 4 places
(which is basically saying divide it by 16)
0xf - is hexidecimal 'f' or decimal 15 or binary 1111
& 0xf - is using '0xf' as what is called a mask. The '&'
means to do a boolean AND function. In this case,
they are only interested in the 4 least significant
bits of 'x' so they AND it with '0xf' which contains
all zero's except the four least significant bits.
Anything AND'ed with zero is zero.
(char) - Means to 'cast' the final answer to be of type 'char'.
So as an example, lets say:
x = 319 (decimal) = 0x13f (hex) = 0000000100111111 (binary)
shifting right 4 places (x >> 4) =
0000000000010011 = 0x0013 = 19 (dec)
masking off the upper 12 bits ( & 0xf) =
0000000000010011
& 0000000000001111 (the '0xf' mask)
---------------------
0000000000000011 = 0x0003 = 3 (dec)
Therefore 'c' = 0x03.
-Kevin
===========================================================================
To unsubscribe: mailto [EMAIL PROTECTED] with body: "signoff JSP-INTEREST".
For digest: mailto [EMAIL PROTECTED] with body: "set JSP-INTEREST DIGEST".
Some relevant FAQs on JSP/Servlets can be found at:
http://java.sun.com/products/jsp/faq.html
http://www.esperanto.org.nz/jsp/jspfaq.html
http://www.jguru.com/jguru/faq/faqpage.jsp?name=JSP
http://www.jguru.com/jguru/faq/faqpage.jsp?name=Servlets
