some basic questions on C++

[Melvik12]

Hi gurues,
this is a code which I took from somewhere I'm a newbie in C++,I cant get some of its part

void combs(const std::string &remaining_letters, const std::string &prefix, int letters_left_to_choose)
{
  if (letters_left_to_choose <= 0) {
    std::cout << prefix << std::endl;
    return;
  }
  size_t i;
  std::string new_remaining;
  for (i = 0; i < remaining_letters.length(); ++i) {
    new_remaining = remaining_letters.substr(0, i) + remaining_letters.substr(i + 1);
    combs(new_remaining, prefix + remaining_letters[i], letters_left_to_choose - 1);
  }
}

I don't know what is the meaning of substr(i + 1)
can someone explain?
thanks.

[Yasoo]

I don't know anything about std::string, but that looks like "substring" to me - like CString's Mid function. So, substr(i+1) would mean to return the rest of the string starting at position i+1 (same as Right(i+1))

[Bob Davis]

Yasoo is correct. std::string::substr() returns a substring of the given string.

[Vedam Shashank]

I don't know what is the meaning of substr(i + 1)

if u observe in ur code, u will find that it is a member of string class.

basic_string substr(size_type pos = 0,
size_type n = npos) const;
The member function returns an object whose controlled sequence is a copy of up to n elements of the controlled sequence beginning at position pos.

Substr will extract, n elements starting from pos. For eg:

std::string str = "YOU ARE NOT WELCOME TO EARTH";
std::string newStr = str.substr(12);

Starting from 12'th position, extract remaining elements (position is zero based)
So 12th position element is "W", and newStr will hold "WELCOME TO EARTH"

std::string str = "YOU ARE NOT WELCOME TO EARTH";
std::string newStr = str.substr(12, 7);

Starting from 12'th position, extract the next 7 elements (position is zero based)
So 12th position element is "W", and newStr will hold "WELCOME"