The '++' operator. !!! HELP !!!

[j.sreejit]

Hi friends,
I am new to the C language and need some help with the increment operator '++'. Please check the following code snippet:

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

The output :

i++ + i++ = 0
i++ + i++ = 1

I do not understand the difference in the output of the operator. Please help.
Thank you.

[major_small]

in other words, "don't do that"

[j.sreejit]

i know

i++ + i++

is bad programming practice because of the ambiguity. I am only a beginner so it confuses me to see such statements and it terrifies me when i realise that i would have to answer similar questions (set to confuse students) in an exam i am about to take towards the end of oct. I want to get such mind blocks out of the way as soon as possible with advanced topics about to come. Please don't mind if ask questions which seem very useless.

[quzah]

It's not ambiguous, it's undefined behaviour.


Quzah.

[Salem]

http://c-faq.com/expr/evalorder2.html
Learn about side effects, modification rules and sequence points.