Why answer is 19?

Question

#include <iostream>
using namespace std;

int main()
{
int x, i=4;
x=++i + ++i + ++i;
cout <<x;
return 0;
}

Answer 1

see here for more information regarding this undefined behaviour.

http://en.cppreference.com/w/cpp/language/eval_order

Answer 2

I think it does 6 + 6 + 7 (may be in another order)
Know that doing more than one increment/decrement like this is undefined in C/C++ standards so it is compiler dependant. What works with gcc might work differently with clang (same for g++ and clang++)

Answer 3

yep# true
depends on compiler###

Answer 4

in c it's showing answer is 21
Increment the variable I up to break point.
Step 2: Start assigning final value 7 to all variable i in the expression.
So, i=7+7+7=21

Answer 5

yeah... 3 ++i
means 4--5--6--7
now 7+7+7

but here it seems...
5+6+7+1

if two ++i
5+6+1