For Loops Initialization - do we need to identify the variable?

Question

I noticed that in the for loops that the variable that's being used always starts with int.
Does that mean that when doing a for loop, we have to define the variable there and then?
For Example:
| int x=3
|
| for (x=3; x>=9; x++) {
| cout << x << endl;
| } // is this acceptable?

Answer 1

yes your example is acceptable
as in any program u need declared variables and in cpp u can declare variables any where in program at the time u required it and that why in for loop variable is declared there
and it is also for reducing the risk of error i.e.,an defined symbol

Answer 2

Yes you have to declare that it's an int. ( as opposed to JS where you don't have to)

Answer 3

That is done in order to restrict the variable scope to the for loop only.

for (int x=1;x <=9;i++) {
// todo
}

is okay and

int x;
for (x=1;x <=9;i++) {
// todo
}

is also okay

Answer 4

You can omit all the terms inside a for loop statement if you want, but that will lead to an infinite loop.
Based on your example, you could have just written :
int x = 3;
for( ; x >= 9; x++){
// code
}

You don't have to define the variable that needs to meet a condition inside the for loop.

Also, just to mention, based on your input, the for loop will never run (3 is never greater or equal to 9).