q from TestCafe.com

[JayaSiji Gopal]

 
What will the output be ?
         public static void main(String[] args){
         char c = '\u0042';
         switch(c) {
         default:
         System.out.println("Default");
         case 'A':
         System.out.println("A");
         case 'B':
         System.out.println("B");
         case 'C':
         System.out.println("C");
         }
         }
 
Prints Default A,B,C
prints A
prints B,C
prints A,B,C,Default
Prints Default 

I was nt able to answer this q since I didnt know the value of '\0042'
please let me know whether such q come up in the real exam and if so, where can i find a list of such constants?

[Mike Gershman]

'\u0042' is B

Appendix B of the Java Programming Language , 3rd Edition, had a Unicode table. You could also google "Unicode".


There is an exam objective:
State the range of all primitive formats, data types and declare literal values for String and all primitive types using all permitted formats bases and representations.

I personally plan on memorizing all Unicode blocks including Gurmukhi, Gujarati, Oriya, and Telugu, but that might be overkill (lol).
[ December 24, 2004: Message edited by: Mike Gershman ]

[Joe Borderi]

"I wasn't able to answer this q since I didn't know the value of '\u0042' "

A couple of things: first, although you didn't know the value of '\u0042', you should still be able to eliminate the choices that read "prints A", "prints A,B,C,Default", and "prints Default" because those choices do not rely on your knowing the value of '\u0042'; those choices rely on your knowledge of the switch statement. Once you eliminate those choices, you have a 50-50 chance between "Prints Default A,B,C" and "Prints B,C".

Second, in the years that I've been programming, I've memorized only a few values from the ASCII table (which maps into Unicode):

  
Decimal   Octal   Hex    Binary     Value
-------   -----   ---    ------     -----
 000      000    000   00000000      NUL    (Null char.)
 010      012    00A   00001010       LF    (Line Feed)
 013      015    00D   00001101       CR    (Carriage Return)
 032      040    020   00100000       SP    (Space)
 048      060    030   00110000        0    ('0')
 065      101    041   01000001        A    ('A')
 097      141    061   01100001        a    ('a')

Briefly, I've memorized NUL because it is used so much by C/C++ programmers; LF and CR from parsing files, and although I know one is 10 and the other 13, I'm never really sure which is Rosencrantz and which is Guildenstern; (Space) because it is important and an island unto itself; '0' because I can figure out all the other base 10 digits by adding 48 to their offsets; and 'A' and 'a' because similar to numbers, I can figure out all upper and lower case letters by adding 'A' or 'a' to their offsets in the alphabet.

In effect, I can quickly figure out 66 ASCII values by knowing seven values in the ASCII table. These are perhaps also the 66 most commonly found and important to know.

Finally, all I really know from the table are the ASCII values (e.g., 'A') and their decimal equivalents (e.g., 65). I do a quick hex computation as needed.