In C, an if or for applies to the following statement or block. A statement is terminated by a semi-colon. So, in C:

for (i = 0; i < 10; ++i)
  printf("%d\n", i);
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is the same as:

for (i = 0; i < 10; ++i) {
  printf("%d\n", i);
}
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and similarly for other constructs.

Personally, I always uses the braces in these contexts in C (as you must in perl), since I think it makes things clearer and it is more robust to future maintenance, where the potential problem is that someone may try to add a second statement to the loop but forget the braces, in which case what they have done is add a statement after the loop.

Update: to be more correct, some statements aren't terminated by a semi-colon and sorry if that is confusing. Basically, the indentation in the code above is accurate as far as the scope of the if's and for's goes.