Now You're Thinking With Functions

Creating for loops with the same repeated pattern contributes to maintenance burden.

Bad

  bool every_request_valid = true;
  for (const Request request : requests)
  {
    if (!IsValid(request))
    {
      every_request_valid = false;
      break;
    }
  }

  if (every_request_valid)
  {
    // do something
  }

  bool every_user_valid = true;
  for (const User user : users)
  {
    if (!IsValid(user))
    {
      every_user_valid = false;
      break;
    }
  }

  if (every_user_valid)
  {
    // do something
  }

Using higher-order functions can help reduce duplication and make the code easier to read.

Good

  if (std::all_of(requests.begin(), requests.end(), IsValid))
  {
    // do something
  }

  if (std::all_of(users.begin(), users.end(), IsValid))
  {
    // do something
  }

Note

This is not to say that for loops are considered harmful and should never be used. In each case, consider the right tool for the job.