For Loop only two things included C++

Question

Lets say I have

int j = 23;
for (j < 20; j++) {
    //do stuff
}

I know it seems stupid in this context but is this possible? Or do you have to do

int j = 23;
for (j; j < 20; j++) {
    //do stuff
}

Answer 1

You'd typically use an empty initializer:

for (; j < 20; ++j)

Granted, it's just an example, but if j is initialized 23, the for loop will never execute at all.