Detecting string argument in a loop

Question

The program takes a string using getline, and then passes that string to a function where it stores the string into substrings separated by whitespace. I did that just by reading characters with a loop.

However, now I'm trying to pass a second string argument that separates the strings into substrings if the loop encounters characters in the 2nd string argument. This is what I have so far.

#include "std_lib_facilities.h"

vector<string> split(const string& s, const string& w) // w is second argument
{
    vector<string> words;
    string altered;
    for(int i = 0; i < s.length(); ++i)
    {
        altered+=s[i];
        if(i == (s.length()-1)) words.push_back(altered);
        else if(s[i] == ' ')
        {
            words.push_back(altered);
            altered = "";
        }
    }

    return words;
}



int main()
{
    vector<string> words;
    cout << "Enter words.\n";
    string word;
    getline(cin,word);
    words = split(word, "aeiou"); // this for example would make the letters a, e, i, o,
                                  // and u divide the string
    for(int i = 0; i < words.size(); ++i)
            cout << words[i];
    cout << endl;
    keep_window_open();
}

However, obviously I can't do something like

if(s[i] == w)

because s[i] is a char and w is a string. Do I need to use a stringstream to parse the string instead of the loop I implemented? I actually played around with stringstream, but don't really know how it could help because either way I have to read the characters 1 by 1.

P.S. The arguments to split must be passed as strings, and the input form in main() must be a getline.

Answer 1

Look at std::string::find_first_of. This allows you to easily ask a std::string object for the position of the next of any characters in another string object.

For example:

string foo = "This is foo";
cout << foo.find_first_of("aeiou"); // outputs 2, the index of the 'i' in 'This'
cout << foo.find_first_of("aeiou", 3); // outputs 5, the index of the 'i' in 'is'

Edit: whoops, wrong link

Answer 2

You can use strtok for this purpose. It is already implemented in STL libraries.

#include 
#include 

int main ()
{
  char str[] ="- This, a sample string.";
  char * pch;
  printf ("Splitting string \"%s\" into tokens:\n",str);
  pch = strtok (str," ,.-");
  while (pch != NULL)
  {
    printf ("%s\n",pch);
    pch = strtok (NULL, " ,.-");
  }
  return 0;
}