为什么当 i++ 定义为 for 循环中的增量时没有立即增量，而它反映在 if 语句的情况下？

Question

I'm just a beginner at C++ and I came across this instance.

#include <iostream>
using namespace std;
int main(){
  int c = 3;
  int d = c++;
  if (c++ == 4 && d == 3)
    cout << "1: " << c << " " << d << endl;
  if (++c == 5 && d-- == 3)
    cout << "2: " << c-- << " " << d << endl;
  cout << "3: " << c << " " << d << endl;
}

So in this case, the output would be:

1: 5 3
3: 6 3 

And what I understand from this is that the variables would still be updated even if they are being called for an increment in the if statement.

Now I came across this:

#include <iostream>
using namespace std:
int main(){
   for (int i= 1; i <= 10; ++i){
     cout << i ;
     break
   }
}

And even though its being incremented it's only returning 1. So I thought that maybe the 2nd time it goes through the loop (after removing the break of course) it would return 3, cause then it would have passed through ++i twice, but it's still 2. I don't understand. So my question is why would there be an instant increment in the if statement but there is none when ++i exists in the for loop ?

EDIT: just fixed a typo. I was supposed to type semicolon but put a comma instead :b

EDIT: added a more straightforward question as some are wondering what I am asking.

Answer 1

A for statement has 4 parts, they are not in the order they are executed.

for ( init-statement condition; iteration_expression) statement

Is defined as equivalent to

{
    init_statement
    while ( condition ) {
        statement
        iteration_expression ;
    }
}

Except that

1. Names declared by the init-statement (if init-statement is a declaration) and names declared by condition (if condition is a declaration) are in the same scope (which is also the scope of statement ).
2. continue in the statement will execute iteration_expression
3. Empty condition is equivalent to while(true)