The question about : j=j++

[Jonh yang]

Hi.. i am really a newbie, just a java beginner.
I need some help.
After executing the statement:j = j ++;
i found that the value of "j" wouldn't increase...but why ?

[Jeanne Boyarsky]

Either of the following will increment j:

j++;
j = ++j;

When using j = j++, it is adding one to j and overwriting it with the original value.

[Marilyn de Queiroz]

Almost. If you look at the output of javap, I think you will see that in the case of j = j++, j is incremented after the value of 'j' is stored. On the other hand, in the case of j = ++j, j is incremented first and then the resulting value is stored in 'j'.

[Davy Kelly]

check out this thread:
post increment
davy

[Jeroen Wenting]

what you're doing is effectivel this:

int t = j;
j++;
j = t;

though the compiler may optimise the whole thing away
j = ++j; would lead to

j = j+1;

[Mr. C Lamont Gilbert]

If you want a specific anser you can always look in the JLS. I believe java behaves differently that c in this respect.

[Jos� Alberto Mu�iz Navarro]

Yeah. in Microsoft's C compiler you get an output of 1 when you do

int i = 0; 
i = i++; 
printf("%d", a);

However, you get an output of 0 when you do

int i = 0; 
int b = i++; 
printf("%d", b);