SCJP : query regarding increment/decrement operator.

[ankur trapasiya]

Hello... I am preparing for SCJP and i found one difficulty regarding operators.

for e.g. in a compound statement like a[i++][++i] or statements like this .... (assume i as integer).

so i am confused about that when actually value of i will be incremented here and how this entire statement will be evaluated by the compiler. In Kathy sierra and Bert Bates book there is very less details are given . can any one prefer any material to understand this or can make me understand this topic ?

Thank you in advance...

[Matthew Brown]

In this sort of case I'd suggest trying it to see what happens. Try this (not checked):

class TestIncrement {
    public static void main(String[] args) {
        String[][] a = {{"0-0", "0-1", "0-2", "0-3"},
            {"1-0", "1-1", "1-2", "1-3"},
            {"2-0", "2-1", "2-2", "2-3"},
            {"3-0", "3-1", "3-2", "3-3"}};
    	    
        int i = 1;
    	
        System.out.println(a[i++][++i]);
    }
}

[Ahmed Attyah]

i++ : Simply i++ means it reads the value then increments it which means it will return the original value but "i" itself incremented

public static void main(String[] args) {
            int i = 1;
            System.out.println(++i);
            System.out.println(i);
        }

++i : it increments i then reads it , it will retrun value of increment

public static void main(String[] args) {
            int i = 1;
            System.out.println(i++);
            System.out.println(i);
        }

so, both increment the value of i but the difference is in return value , i++ returns original value , ++i return value after increment.

Note: i don't think this is the appropriate forum for SCJP Questions

[ankur trapasiya]

dear ahmed. i know pre-increment and post increment operations pretty good but the thing i wanted to know was that the order in which these operations are carried out..

e.g. int j =12; i= ++j + j++ * ++j ;

something like this. that's why i asked this question to know the flow this execution...

Thanks for your posts.

[Imad Aydarooos]

int j =12; i= ++j + j++ * ++j ;
the order is from left to right:
1- First all your j's will be inialized as follws i = 13 + 13 * 15. and you end up with j=15
2- the arithmatic operation carried out as i = 208

(why all these smiles to someone who want to let us know more)

[ankur trapasiya]

hey Imad...!!! Thanks a lot... my doubt got cleared and please dont mind putting similes in my lines is my habit .