please help me

[jigart4586]

hi, i a m jigar thakkar
please help me.

int a=1;
printf("%d%d%d",a++,a++,a++);
output : 3,2,1

how work this in c?
please explain in detail?

Thanx in advance.

[jigart4586]

Hi, inteligent people,
i m jgiar thakkar
please help me on this :

int a=1;
printf("%d%d%d",a++,a++,a++);
output : 3,2,1

Please help how work this actually>?
Explain reason in detail.

Thanx in advance

[WaltP]

It doesn't. See http://c-faq.com/expr/evalorder2.html

[Duoas]

Best answer is, don't do that.

You are playing with undefined behavior. For any single variable, there should be a maximum of one pre/post increment/decrement operator. Otherwise your results may vary: You could just as easily have gotten 1 2 3, 1 3 2, 3 1 2, 2 1 3, or 2 3 1.

The actual reason you are getting 3 2 1 is because your compiler plays with the arguments in the same order they must be pushed onto the stack to call a c-function. However, that's just one compiler. Others could easily give you different results. (Heck, the same compiler could give you different results at different times.)

Therefore, better to say:

int a = 1;
printf( "%d%d%d", a, a+1, a+2 );
a += 3;

This avoids the undefined behavior of multiple pre/post inc/dec ops for a single variable in one statement.

Hope this helps.

[WaltP]

Don't double post

[Ancient Dragon]

merged two threads and moved to C board.