You wrote a while loop and the body never runs. What are the most likely causes?

Three things to check, in order. First, the condition starts false, the variables it tests already have values that make it false before the first iteration; add a printf or step in the debugger to confirm. Second, you put the condition test before initializing the variable, common when you copy/paste loops around. Third, in do-while vs while confusion: a do-while body always runs once, so if "the body never runs" really means "the body runs exactly once when I expected zero," you might be using the wrong form. The systematic fix is to print the values of every variable in the condition right before the loop, so you can see what the condition is actually testing.