C++ Cookbook

4.6. Splitting a String

Problem

You want to split a delimited string into multiple strings. For example, you may want to split the string "Name|Address|Phone" into three separate strings, "Name“, "Address“, and "Phone“, with the delimiter removed.

Solution

Use basic_string’s find member function to advance from one occurrence of the delimiter to the next, and substr to copy each substring out of the original string. You can use any standard sequence to hold the results; Example 4-10 uses a vector.

Example 4-10. Split a delimited string

#include <string>
#include <vector>
#include <functional>
#include <iostream>

using namespace std;

void split(const string& s, char c,
           vector<string>& v) {
   string::size_type i = 0;
   string::size_type j = s.find(c);

   while (j != string::npos) {
      v.push_back(s.substr(i, j-i));
      i = ++j;
      j = s.find(c, j);

      if (j == string::npos)
         v.push_back(s.substr(i, s.length()));
   }
}

int main() {
   vector<string> v;
   string s = "Account Name|Address 1|Address 2|City";

   split(s, '|', v);

   for (int i = 0; i < v.size(); ++i) {
      cout << v[i] << '\n';
   }
}

Discussion

Making the example above a function template that accepts any kind of character is trivial; just parameterize the character type and change references to string to basic_string<T>:

template<typename T> void split(const basic_string<T>& s, T c, vector<basic_string<T> >& v) { basic_string<T>::size_type i = 0; basic_string<T>::size_type j = s.find(c); while (j != basic_string<T>::npos) { v.push_back(s.substr(i, j-i)); i = ++j; ...