c = a+(b++); printf("output:c=%d\tb=%d\n",c,b); = 4,3

Question

Code:

{
  int a =2,b=2,c=0;
  c = a+(b++);

  printf("output:c=%d\tb=%d\n",c,b);
}

Output:

output: c=4      b=3

How output of c = 4 here, My understanding is c=5, can any one explain it please?

[This](https://stackoverflow.com/questions/7031326/what-is-the-difference-between-prefix-and-postfix-operators) is why. — squiguy, Nov 19 '14 at 21:46
@Engine wait, are you telling me that new users' questions shouldn't be downvoted if they lack research effort (as this question clearly does)? — The Paramagnetic Croissant, Nov 19 '14 at 22:05
@engine the explanatory text of the closure already does that. downvoting does not exist for the purpose of welcoming new users. it exists for expressing towards the community that a qestion doesn't meet the site's quality standards. — The Paramagnetic Croissant, Nov 20 '14 at 05:57

score 3 · Answer 1 · edited May 23 '17 at 10:33

3

Because there is a difference between ++i and i++!

Prefix/ Postfix

++i  // `Prefix` gets incremented `before` it get's used (e.g. in a operation)
i++  // `Postfix` gets incremented `after` it get's used (e.g. in a operation)

So that's why c is 4!

If you change b++ to ++b then c gets 5!

See also:

What is the difference between prefix and postfix operators?

edited May 23 '17 at 10:33

Community

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answered Nov 19 '14 at 21:54

Rizier123

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score 2 · Answer 2 · answered Nov 19 '14 at 21:57

I don't think b++ is quite doing what you think it is. c = a+(b++) says "c equals a plus b then increment b by one", therefore c will be 4. If you use ++b instead, b will be incremented before the addition and c will be 5.

c = a+(b++); // c = 4
c = a+(++b); // c = 5

After each of these lines b will be 3, the only thing that changes between them is when b becomes 3.

c = a+(b++); printf("output:c=%d\tb=%d\n",c,b); = 4,3

Code:

Output:

2 Answers2