Tokenizing a String, break a string into pieces using a set of delimiters. - C++ STL

C++ examples for STL:string

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Description

Tokenizing a String, break a string into pieces using a set of delimiters.

Demo Code

#include <string>
#include <iostream>

using namespace std;

class StringTokenizer {
public:/*  ww  w  .j a v  a 2s. co m*/
   StringTokenizer(const string& s, const char* delim = NULL) : str_(s), count_(-1), begin_(0), end_(0) {
      if (!delim)
         delim_ = " \f\n\r\t\v";  //default to whitespace
      else
         delim_ = delim;

      // Point to the first token
      begin_ = str_.find_first_not_of(delim_);
      end_ = str_.find_first_of(delim_, begin_);
   }

   size_t countTokens() {
     if (count_ >= 0) // return if we've already counted
       return(count_);

     string::size_type n = 0;
     string::size_type i = 0;

     for (;;) {
        // advance to the first token
        if ((i = str_.find_first_not_of(delim_, i)) == string::npos)
           break;
        // advance to the next delimiter
        i = str_.find_first_of(delim_, i+1);
        n++;
        if (i == string::npos)
          break;
     }
     return (count_ = n);
   }
   bool hasMoreTokens() {
      return(begin_ != end_);
   }
   void nextToken(string& s) {
     if (begin_ != string::npos && end_ != string::npos) {
        s = str_.substr(begin_, end_-begin_);
        begin_ = str_.find_first_not_of(delim_, end_);
        end_ = str_.find_first_of(delim_, begin_);
     }
     else if (begin_ != string::npos && end_ == string::npos)
     {
        s = str_.substr(begin_, str_.length()-begin_);
        begin_ = str_.find_first_not_of(delim_, end_);
     }
   }
private:
   StringTokenizer() {};
   string delim_;
   string str_;
   int count_;
   int begin_;
   int end_;
};

int main() {
   string s = " this is a test ";
   string tmp;

   StringTokenizer st(s);

   cout << "there are " << st.countTokens() << " tokens.\n";
   while (st.hasMoreTokens()) {
      st.nextToken(tmp);
      cout << "token = " << tmp << '\n';
   }
}

Result


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