Couple quick questions about octel and hex notation

[David Miranda]

Hi all,

Im trying to understand what the '0x' in lets say 0x0F stands for...

Does the '0x' just stand for 'this is hex'?

Also...

Lets say we have a number '010'...this is octel. Is putting a '0' in front of a number the only way to signify that a number is octel?

Thanks!

Dave

[Ernest Friedman-Hill]

Originally posted by David Miranda:

Does the '0x' just stand for 'this is hex'?

Yes, that's all.

Lets say we have a number '010'...this is octel. Is putting a '0' in front of a number the only way to signify that a number is octel?

Yes.

[David Miranda]

Great, thanks!

[Ryan McGuire]

Simulpost! Oh well, I'll leave this here for the joke at the end if nothing else.
-------------------
Yes, 0x or 0X means this is a hexadecimal number.
And yes, just a leading 0 is the only way to make an octal integer contstant.

0x0c == 014 == 12

The thing that trips many people up is using leading zeros to make columns line up:

public final static int CHRISTMAS = 1225;
public final static int HALLOWEEN = 1030;
public final static int GROUNDHOG = 0202;
public int getMonth(int date) { return date/100; }
public int getDay  (int date) { return date%100; }
public String formatDate(int date) { 
    return getMonth(date) + "/" + getDat(date);
}

formatDate(CHRISTMAS) returns "12/25"
formatDate(HALLOWEEN) returns "10/30"
but formatDate(GROUNDHOG) returns "1/30"

The final static declarations should have been...

public final static int CHRISTMAS = 1225;
public final static int HALLOWEEN = 1030;
public final static int GROUNDHOG =  202;

But octal and hex are handy for defining bits. Compare...

public final static int OTHERSX = 0001;
public final static int OTHERSW = 0002;
public final static int OTHERSR = 0004;
public final static int GROUPX  = 0010;
public final static int GROUPW  = 0020;
public final static int GROUPR  = 0040;
public final static int OWNERX  = 0100;
public final static int OWNERW  = 0200;
public final static int OWNERR  = 0400;

to...

public final static int OTHERSX = 1;
public final static int OTHERSW = 2;
public final static int OTHERSR = 4;
public final static int GROUPX  = 8;
public final static int GROUPW  = 16;
public final static int GROUPR  = 32;
public final static int OWNERX  = 64;
public final static int OWNERW  = 128;
public final static int OWNERR  = 256;

Ryan


P.S. This talk of holidays reminds me of a riddle:

Why do programmers get Halloween and Christmas mixed up?







Because 31 Oct = 25 Dec
[ April 15, 2005: Message edited by: Ryan McGuire ]