Why is it that I can't use == in a For loop?

Question

I don't know if that's been asked before, but I haven't been able to find an answer, nonetheless. My question is this; in For loops, this is acceptable.

int k = 0;

for (int i = 0; i <= 10; i++)
    k++;

But this is NOT:

int k = 0;

for (int i = 0; i == 10; i++)
    k++;

Why is it that I cannot use '==' to determine whether the condition has been met? I mean, both expressions return true or false depending on the situation and the latter would be appropriate for, say, an If loop.

int k = 10;

if (k == 10)
{
    // Do stuff.
}

The answer to this question has been bothering me for a good while now during my time as a hobbyist programmer, but I hadn't searched for it till now.

Answer 1

A for loop will run while the condition is satisfied. At the beginning i = 0, so your test i == 10 is never satisfied and thus the body of the loop is never executed.

On the other hand you could have used i == 0 condition and the loop would have executed only once:

for (int i = 0; i == 0; i++)
    k++;

That's the reason why if you want a for loop to execute more than once, you need to provide a condition for the iterator variable that is < or > so that it can be satisfied more than once while this iterator variable increments/decrements.