Recently I was questioned about a test in C that I couldn´t find the answer. Can anybody Help me to find it?

Code:
...
int i,num = 42;
for (i=0 ; i < num ; i--)
  printf("*");
...
The intent is print 42 *. the question is : "Can you fix this code changing just one character? You can insert OR remove OR change just one character of code. "
i++ would solve the problem ,so certainly it has something with boolean operators... As it was not enougth the problem pointed that there were 3 solutions , how many can you see?
thank you.