Because the expressions are in the wrong order. You say:
Set i=1.
if (i > 0) continue, and increase the value of i by 1.
At the end of each loop test i < 100, but take no action.
What you should be writing is:
for (i = start value; while expression involving i; do something with i)
So for what you seem to be trying to do it would be
for (i = 0; i < 100; i++)
{
}