Declaring variables in C/C++

Question

Someone told me: "declaring variables close to their use have value". He corrected me:

void student_score(size_t student_list_size) {
  // int exam;
  // int average;
  // int digit;
  // int counter_digits;

  for (size_t i = 0; i < student_list_size; i++) {
    int exam;
    int average;
    int digit;
    int counter_digits;

I think it's bad, because here variables initialized every loop. What's true?

Answer 1

I encourage to declare them in as local a scope as possible, and as close to the first use as possible. This makes it easier for the reader to find the declaration and see what type the variable is and what it was initialized to. And of course, compiler will optimize it.