source: doc/theses/mike_brooks_MMath/word.cc@ a7b78c3

#include <string>
#include <iostream>
using namespace std;
int main() {
        string line, alpha = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
        size_t i;

        for ( ; getline( cin, line ); ) {
                for ( ;; ) {                                                                    // scan words off line
                        string::size_type posn = line.find_first_of( alpha );// find position of 1st alphabetic character
                  if ( posn == string::npos ) break;                    // any characters left ?
                        line = line.substr( posn );                                     // remove leading whitespace
                        posn = line.find_first_not_of( alpha );         // find position of 1st non-alphabetic character
                        if ( posn != string::npos ) {
                                cout << line.substr( 0, posn ) << endl; // extract word from start of line
                                line = line.substr( posn );                             // delete word from line
                        } else {
                                cout << line << endl;                                   // extract word from start of line
                                line = "";
                        }
                } // for
        } // for
}