++k and k++ are different processes, or not?

I noticed a problem when I glanced at my studying document. The problem is about post and pre increment operator ++.

Here are the code in mydocument:

Code:

---

#include <iostream>
#include <conio.h>


using namespace std;


int k = 0; //global k


int main()
{
    int k; //local k


    for (k = 0; k < 10; k++) {  // LOOK AT HERE !!!!!!!!!!!!!!!!!!!!
          cout << " local variable " << k ;
          cout << " global variable " << ::k <<endl;
    }


    ::k++;


    cout << endl;


    cout << " After loop;\n" ;
    cout << " local variable : " << k ;
    cout << "\n global variable : " << ::k <<endl;


    getch();


    return 0;
}

---

Here are the output:
Attachment 13171

So what if the for loop was that ;
for (k = 0; k < 10; ++k)
Does the output change ?

I expect the same output except for line 1 in the output:
local variable 1 global variable 0

Then,
---------------------------------
local variable 2 global variable 0
local variable 3 global variable 0
...
bla bla bla
...
---------------------------------
Why the k is not 1 in the first looping in for loop ? Or is k++ and ++k the same thing? I know that these are different. But there are as if the same. Can anybody solve this problem in my mind?

> for (k = 0; k < 10; ++k)
> Does the output change ?
No, because whether you write k++ or ++k, it still happens after the body of the loop has executed.

If you're just using it for the side effect of incrementing the variable, there is no difference at all (for the built-in types(*)).
You only see the difference when you inspect the value of k with the side effect applied.

Compare
int a = k++;
int b = ++k;
Now compare a, b and k



(*)When you come to overload the operators in a C++ class however, you should be mindful of the differences.

Okay, I understand. Thank you for your answer.