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

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

Code:

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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 :

Code:

---

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

---

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

in other words, "don't do that"

i know

Code:

---

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.

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


Quzah.

http://c-faq.com/expr/evalorder2.html
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