How do I iterate over the words of a string?

Question

How do I iterate over the words of a string composed of words separated by whitespace?

Note that I'm not interested in C string functions or that kind of character manipulation/access. I prefer elegance over efficiency. My current solution:

#include <iostream>
#include <sstream>
#include <string>

using namespace std;

int main() {
    string s = "Somewhere down the road";
    istringstream iss(s);

    do {
        string subs;
        iss >> subs;
        cout << "Substring: " << subs << endl;
    } while (iss);
}

Answer 1

I use this to split string by a delimiter. The first puts the results in a pre-constructed vector, the second returns a new vector.

#include <string>
#include <sstream>
#include <vector>
#include <iterator>

template <typename Out>
void split(const std::string &s, char delim, Out result) {
    std::istringstream iss(s);
    std::string item;
    while (std::getline(iss, item, delim)) {
        *result++ = item;
    }
}

std::vector<std::string> split(const std::string &s, char delim) {
    std::vector<std::string> elems;
    split(s, delim, std::back_inserter(elems));
    return elems;
}

---

Note that this solution does not skip empty tokens, so the following will find 4 items, one of which is empty:

std::vector<std::string> x = split("one:two::three", ':');

Answer 2

For what it's worth, here's another way to extract tokens from an input string, relying only on standard library facilities. It's an example of the power and elegance behind the design of the STL.

#include <iostream>
#include <string>
#include <sstream>
#include <algorithm>
#include <iterator>

int main() {
    using namespace std;
    string sentence = "And I feel fine...";
    istringstream iss(sentence);
    copy(istream_iterator<string>(iss),
         istream_iterator<string>(),
         ostream_iterator<string>(cout, "\n"));
}

Instead of copying the extracted tokens to an output stream, one could insert them into a container, using the same generic copy algorithm.

vector<string> tokens;
copy(istream_iterator<string>(iss),
     istream_iterator<string>(),
     back_inserter(tokens));

... or create the vector directly:

vector<string> tokens{istream_iterator<string>{iss},
                      istream_iterator<string>{}};

Answer 3

A possible solution using Boost might be:

#include <boost/algorithm/string.hpp>
std::vector<std::string> strs;
boost::split(strs, "string to split", boost::is_any_of("\t "));

This approach might be even faster than the stringstream approach. And since this is a generic template function it can be used to split other types of strings (wchar, etc. or UTF-8) using all kinds of delimiters.

See the documentation for details.

Answer 4

#include <vector>
#include <string>
#include <sstream>

int main()
{
    std::string str("Split me by whitespaces");
    std::string buf;                 // Have a buffer string
    std::stringstream ss(str);       // Insert the string into a stream

    std::vector<std::string> tokens; // Create vector to hold our words

    while (ss >> buf)
        tokens.push_back(buf);

    return 0;
}

Answer 5

An efficient, small, and elegant solution using a template function:

template <class ContainerT>
void split(const std::string& str, ContainerT& tokens,
           const std::string& delimiters = " ", bool trimEmpty = false)
{
   std::string::size_type pos, lastPos = 0, length = str.length();
   
   using value_type = typename ContainerT::value_type;
   using size_type = typename ContainerT::size_type;
   
   while (lastPos < length + 1)
   {
      pos = str.find_first_of(delimiters, lastPos);
      if (pos == std::string::npos)
         pos = length;

      if (pos != lastPos || !trimEmpty)
         tokens.emplace_back(value_type(str.data() + lastPos,
               (size_type)pos - lastPos));

      lastPos = pos + 1;
   }
}

I usually choose to use std::vector<std::string> types as my second parameter (ContainerT)... but list<...> may sometimes be preferred over vector<...>.

It also allows you to specify whether to trim empty tokens from the results via a last optional parameter.

All it requires is std::string included via <string>. It does not use streams or the boost library explicitly but will be able to accept some of these types.

Also since C++-17 you can use std::vector<std::string_view> which is much faster and more memory-efficient than using std::string. Here is a revised version which also supports the container as a return type:

#include <vector>
#include <string_view>
#include <utility>
    
template < typename StringT,
           typename DelimiterT = char,
           typename ContainerT = std::vector<std::string_view> >
ContainerT split(StringT const& str, DelimiterT const& delimiters = ' ', bool trimEmpty = true, ContainerT&& tokens = {})
{
    typename StringT::size_type pos, lastPos = 0, length = str.length();

    while (lastPos < length + 1)
    {
        pos = str.find_first_of(delimiters, lastPos);
        if (pos == StringT::npos)
            pos = length;

      if (pos != lastPos || !trimEmpty)
            tokens.emplace_back(str.data() + lastPos, pos - lastPos);

        lastPos = pos + 1;
    }

    return std::forward<ContainerT>(tokens);
}

Care has been taken not to make any unneeded copies.

This will allow for either:

for (auto const& line : split(str, '\n'))

Or:

auto& lines = split(str, '\n');

Both returning the default template container type of std::vector<std::string_view>.

To get a specific container type back, or to pass an existing container, use the tokens input parameter with either a typed initial container or an existing container variable:

auto& lines = split(str, '\n', false, std::vector<std::string>());

Or:

std::vector<std::string> lines;
split(str, '\n', false, lines);

Answer 6

Here's another solution. It's compact and reasonably efficient:

std::vector<std::string> split(const std::string &text, char sep) {
  std::vector<std::string> tokens;
  std::size_t start = 0, end = 0;
  while ((end = text.find(sep, start)) != std::string::npos) {
    tokens.push_back(text.substr(start, end - start));
    start = end + 1;
  }
  tokens.push_back(text.substr(start));
  return tokens;
}

It can easily be templatised to handle string separators, wide strings, etc.

Note that splitting "" results in a single empty string and splitting "," (ie. sep) results in two empty strings.

It can also be easily expanded to skip empty tokens:

std::vector<std::string> split(const std::string &text, char sep) {
    std::vector<std::string> tokens;
    std::size_t start = 0, end = 0;
    while ((end = text.find(sep, start)) != std::string::npos) {
        if (end != start) {
          tokens.push_back(text.substr(start, end - start));
        }
        start = end + 1;
    }
    if (end != start) {
       tokens.push_back(text.substr(start));
    }
    return tokens;
}

---

If splitting a string at multiple delimiters while skipping empty tokens is desired, this version may be used:

std::vector<std::string> split(const std::string& text, const std::string& delims)
{
    std::vector<std::string> tokens;
    std::size_t start = text.find_first_not_of(delims), end = 0;

    while((end = text.find_first_of(delims, start)) != std::string::npos)
    {
        tokens.push_back(text.substr(start, end - start));
        start = text.find_first_not_of(delims, end);
    }
    if(start != std::string::npos)
        tokens.push_back(text.substr(start));

    return tokens;
}

Answer 7

This is my favorite way to iterate through a string. You can do whatever you want per word.

string line = "a line of text to iterate through";
string word;

istringstream iss(line, istringstream::in);

while( iss >> word )     
{
    // Do something on `word` here...
}

Answer 8

This is similar to Stack Overflow question How do I tokenize a string in C++?. Requires Boost external library

#include <iostream>
#include <string>
#include <boost/tokenizer.hpp>

using namespace std;
using namespace boost;

int main(int argc, char** argv)
{
    string text = "token  test\tstring";

    char_separator<char> sep(" \t");
    tokenizer<char_separator<char>> tokens(text, sep);
    for (const string& t : tokens)
    {
        cout << t << "." << endl;
    }
}

Answer 9

I like the following because it puts the results into a vector, supports a string as a delim and gives control over keeping empty values. But, it doesn't look as good then.

#include <ostream>
#include <string>
#include <vector>
#include <algorithm>
#include <iterator>
using namespace std;

vector<string> split(const string& s, const string& delim, const bool keep_empty = true) {
    vector<string> result;
    if (delim.empty()) {
        result.push_back(s);
        return result;
    }
    string::const_iterator substart = s.begin(), subend;
    while (true) {
        subend = search(substart, s.end(), delim.begin(), delim.end());
        string temp(substart, subend);
        if (keep_empty || !temp.empty()) {
            result.push_back(temp);
        }
        if (subend == s.end()) {
            break;
        }
        substart = subend + delim.size();
    }
    return result;
}

int main() {
    const vector<string> words = split("So close no matter how far", " ");
    copy(words.begin(), words.end(), ostream_iterator<string>(cout, "\n"));
}

Of course, Boost has a split() that works partially like that. And, if by 'white-space', you really do mean any type of white-space, using Boost's split with is_any_of() works great.

Answer 10

The STL does not have such a method available already.

However, you can either use C's strtok() function by using the std::string::c_str() member, or you can write your own. Here is a code sample I found after a quick Google search ("STL string split"):

void Tokenize(const string& str,
              vector<string>& tokens,
              const string& delimiters = " ")
{
    // Skip delimiters at beginning.
    string::size_type lastPos = str.find_first_not_of(delimiters, 0);
    // Find first "non-delimiter".
    string::size_type pos     = str.find_first_of(delimiters, lastPos);

    while (string::npos != pos || string::npos != lastPos)
    {
        // Found a token, add it to the vector.
        tokens.push_back(str.substr(lastPos, pos - lastPos));
        // Skip delimiters.  Note the "not_of"
        lastPos = str.find_first_not_of(delimiters, pos);
        // Find next "non-delimiter"
        pos = str.find_first_of(delimiters, lastPos);
    }
}

Taken from: http://oopweb.com/CPP/Documents/CPPHOWTO/Volume/C++Programming-HOWTO-7.html

If you have questions about the code sample, leave a comment and I will explain.

And just because it does not implement a typedef called iterator or overload the << operator does not mean it is bad code. I use C functions quite frequently. For example, printf and scanf both are faster than std::cin and std::cout (significantly), the fopen syntax is a lot more friendly for binary types, and they also tend to produce smaller EXEs.

Don't get sold on this "Elegance over performance" deal.

Answer 11

Here is a split function that:

• is generic
• uses standard C++ (no boost)
• accepts multiple delimiters

• ignores empty tokens (can easily be changed)

  template<typename T>
  vector<T> 
  split(const T & str, const T & delimiters) {
      vector<T> v;
      typename T::size_type start = 0;
      auto pos = str.find_first_of(delimiters, start);
      while(pos != T::npos) {
          if(pos != start) // ignore empty tokens
              v.emplace_back(str, start, pos - start);
          start = pos + 1;
          pos = str.find_first_of(delimiters, start);
      }
      if(start < str.length()) // ignore trailing delimiter
          v.emplace_back(str, start, str.length() - start); // add what's left of the string
      return v;
  }
  

Example usage:

    vector<string> v = split<string>("Hello, there; World", ";,");
    vector<wstring> v = split<wstring>(L"Hello, there; World", L";,");

Answer 12

I have a 2 lines solution to this problem:

char sep = ' ';
std::string s="1 This is an example";

for(size_t p=0, q=0; p!=s.npos; p=q)
  std::cout << s.substr(p+(p!=0), (q=s.find(sep, p+1))-p-(p!=0)) << std::endl;

Then instead of printing you can put it in a vector.

Answer 13

Yet another flexible and fast way

template<typename Operator>
void tokenize(Operator& op, const char* input, const char* delimiters) {
  const char* s = input;
  const char* e = s;
  while (*e != 0) {
    e = s;
    while (*e != 0 && strchr(delimiters, *e) == 0) ++e;
    if (e - s > 0) {
      op(s, e - s);
    }
    s = e + 1;
  }
}

To use it with a vector of strings (Edit: Since someone pointed out not to inherit STL classes... hrmf ;) ) :

template<class ContainerType>
class Appender {
public:
  Appender(ContainerType& container) : container_(container) {;}
  void operator() (const char* s, unsigned length) { 
    container_.push_back(std::string(s,length));
  }
private:
  ContainerType& container_;
};

std::vector<std::string> strVector;
Appender v(strVector);
tokenize(v, "A number of words to be tokenized", " \t");

That's it! And that's just one way to use the tokenizer, like how to just count words:

class WordCounter {
public:
  WordCounter() : noOfWords(0) {}
  void operator() (const char*, unsigned) {
    ++noOfWords;
  }
  unsigned noOfWords;
};

WordCounter wc;
tokenize(wc, "A number of words to be counted", " \t"); 
ASSERT( wc.noOfWords == 7 );

Limited by imagination ;)

Answer 14

Here's a simple solution that uses only the standard regex library

#include <regex>
#include <string>
#include <vector>

std::vector<std::string> Tokenize( const string str, const std::regex regex )
{
    using namespace std;

    std::vector<string> result;

    sregex_token_iterator it( str.begin(), str.end(), regex, -1 );
    sregex_token_iterator reg_end;

    for ( ; it != reg_end; ++it ) {
        if ( !it->str().empty() ) //token could be empty:check
            result.emplace_back( it->str() );
    }

    return result;
}

The regex argument allows checking for multiple arguments (spaces, commas, etc.)

I usually only check to split on spaces and commas, so I also have this default function:

std::vector<std::string> TokenizeDefault( const string str )
{
    using namespace std;

    regex re( "[\\s,]+" );

    return Tokenize( str, re );
}

The "[\\s,]+" checks for spaces (\\s) and commas (,).

Note, if you want to split wstring instead of string,

• change all std::regex to std::wregex
• change all sregex_token_iterator to wsregex_token_iterator

Note, you might also want to take the string argument by reference, depending on your compiler.

Answer 15

Using std::stringstream as you have works perfectly fine, and do exactly what you wanted. If you're just looking for different way of doing things though, you can use std::find()/std::find_first_of() and std::string::substr().

Here's an example:

#include <iostream>
#include <string>

int main()
{
    std::string s("Somewhere down the road");
    std::string::size_type prev_pos = 0, pos = 0;

    while( (pos = s.find(' ', pos)) != std::string::npos )
    {
        std::string substring( s.substr(prev_pos, pos-prev_pos) );

        std::cout << substring << '\n';

        prev_pos = ++pos;
    }

    std::string substring( s.substr(prev_pos, pos-prev_pos) ); // Last word
    std::cout << substring << '\n';

    return 0;
}

Answer 16

If you like to use boost, but want to use a whole string as delimiter (instead of single characters as in most of the previously proposed solutions), you can use the boost_split_iterator.

Example code including convenient template:

#include <iostream>
#include <vector>
#include <boost/algorithm/string.hpp>

template<typename _OutputIterator>
inline void split(
    const std::string& str, 
    const std::string& delim, 
    _OutputIterator result)
{
    using namespace boost::algorithm;
    typedef split_iterator<std::string::const_iterator> It;

    for(It iter=make_split_iterator(str, first_finder(delim, is_equal()));
            iter!=It();
            ++iter)
    {
        *(result++) = boost::copy_range<std::string>(*iter);
    }
}

int main(int argc, char* argv[])
{
    using namespace std;

    vector<string> splitted;
    split("HelloFOOworldFOO!", "FOO", back_inserter(splitted));

    // or directly to console, for example
    split("HelloFOOworldFOO!", "FOO", ostream_iterator<string>(cout, "\n"));
    return 0;
}

Answer 17

C++20 finally blesses us with a split function. Or rather, a range adapter. Godbolt link.

#include <iostream>
#include <ranges>
#include <string_view>

namespace ranges = std::ranges;
namespace views = std::views;

using str = std::string_view;

auto view =
    "Multiple words"
    | views::split(' ')
    | views::transform([](auto &&r) -> str {
        return str(r.begin(), r.end());
    });

auto main() -> int {
    for (str &&sv : view) {
        std::cout << sv << '\n';
    }
}

Answer 18

Heres a regex solution that only uses the standard regex library. (I'm a little rusty, so there may be a few syntax errors, but this is at least the general idea)

#include <regex.h>
#include <string.h>
#include <vector.h>

using namespace std;

vector<string> split(string s){
    regex r ("\\w+"); //regex matches whole words, (greedy, so no fragment words)
    regex_iterator<string::iterator> rit ( s.begin(), s.end(), r );
    regex_iterator<string::iterator> rend; //iterators to iterate thru words
    vector<string> result<regex_iterator>(rit, rend);
    return result;  //iterates through the matches to fill the vector
}

Answer 19

There is a function named strtok.

#include<string>
using namespace std;

vector<string> split(char* str,const char* delim)
{
    char* saveptr;
    char* token = strtok_r(str,delim,&saveptr);

    vector<string> result;

    while(token != NULL)
    {
        result.push_back(token);
        token = strtok_r(NULL,delim,&saveptr);
    }
    return result;
}

Answer 20

Using std::string_view and Eric Niebler's range-v3 library:

https://wandbox.org/permlink/kW5lwRCL1pxjp2pW

#include <iostream>
#include <string>
#include <string_view>
#include "range/v3/view.hpp"
#include "range/v3/algorithm.hpp"

int main() {
    std::string s = "Somewhere down the range v3 library";
    ranges::for_each(s  
        |   ranges::view::split(' ')
        |   ranges::view::transform([](auto &&sub) {
                return std::string_view(&*sub.begin(), ranges::distance(sub));
            }),
        [](auto s) {std::cout << "Substring: " << s << "\n";}
    );
}

By using a range for loop instead of ranges::for_each algorithm:

#include <iostream>
#include <string>
#include <string_view>
#include "range/v3/view.hpp"

int main()
{
    std::string str = "Somewhere down the range v3 library";
    for (auto s : str | ranges::view::split(' ')
                      | ranges::view::transform([](auto&& sub) { return std::string_view(&*sub.begin(), ranges::distance(sub)); }
                      ))
    {
        std::cout << "Substring: " << s << "\n";
    }
}

Answer 21

The stringstream can be convenient if you need to parse the string by non-space symbols:

string s = "Name:JAck; Spouse:Susan; ...";
string dummy, name, spouse;

istringstream iss(s);
getline(iss, dummy, ':');
getline(iss, name, ';');
getline(iss, dummy, ':');
getline(iss, spouse, ';')

Answer 22

So far I used the one in Boost, but I needed something that doesn't depends on it, so I came to this:

static void Split(std::vector<std::string>& lst, const std::string& input, const std::string& separators, bool remove_empty = true)
{
    std::ostringstream word;
    for (size_t n = 0; n < input.size(); ++n)
    {
        if (std::string::npos == separators.find(input[n]))
            word << input[n];
        else
        {
            if (!word.str().empty() || !remove_empty)
                lst.push_back(word.str());
            word.str("");
        }
    }
    if (!word.str().empty() || !remove_empty)
        lst.push_back(word.str());
}

A good point is that in separators you can pass more than one character.

Answer 23

Short and elegant

#include <vector>
#include <string>
using namespace std;

vector<string> split(string data, string token)
{
    vector<string> output;
    size_t pos = string::npos; // size_t to avoid improbable overflow
    do
    {
        pos = data.find(token);
        output.push_back(data.substr(0, pos));
        if (string::npos != pos)
            data = data.substr(pos + token.size());
    } while (string::npos != pos);
    return output;
}

can use any string as delimiter, also can be used with binary data (std::string supports binary data, including nulls)

using:

auto a = split("this!!is!!!example!string", "!!");

output:

this
is
!example!string

Answer 24

This answer takes the string and puts it into a vector of strings. It uses the boost library.

#include <boost/algorithm/string.hpp>
std::vector<std::string> strs;
boost::split(strs, "string to split", boost::is_any_of("\t "));

Answer 25

I made this because I needed an easy way to split strings and C-based strings. Hopefully someone else can find it useful as well. Also, it doesn't rely on tokens, and you can use fields as delimiters, which is another key I needed.

I'm sure there are improvements that can be made to even further improve its elegance, and please do by all means.

StringSplitter.hpp:

#include <vector>
#include <iostream>
#include <string.h>

using namespace std;

class StringSplit
{
private:
    void copy_fragment(char*, char*, char*);
    void copy_fragment(char*, char*, char);
    bool match_fragment(char*, char*, int);
    int untilnextdelim(char*, char);
    int untilnextdelim(char*, char*);
    void assimilate(char*, char);
    void assimilate(char*, char*);
    bool string_contains(char*, char*);
    long calc_string_size(char*);
    void copy_string(char*, char*);

public:
    vector<char*> split_cstr(char);
    vector<char*> split_cstr(char*);
    vector<string> split_string(char);
    vector<string> split_string(char*);
    char* String;
    bool do_string;
    bool keep_empty;
    vector<char*> Container;
    vector<string> ContainerS;

    StringSplit(char * in)
    {
        String = in;
    }

    StringSplit(string in)
    {
        size_t len = calc_string_size((char*)in.c_str());
        String = new char[len + 1];
        memset(String, 0, len + 1);
        copy_string(String, (char*)in.c_str());
        do_string = true;
    }

    ~StringSplit()
    {
        for (int i = 0; i < Container.size(); i++)
        {
            if (Container[i] != NULL)
            {
                delete[] Container[i];
            }
        }
        if (do_string)
        {
            delete[] String;
        }
    }
};

StringSplitter.cpp:

#include <string.h>
#include <iostream>
#include <vector>
#include "StringSplit.hpp"

using namespace std;

void StringSplit::assimilate(char*src, char delim)
{
    int until = untilnextdelim(src, delim);
    if (until > 0)
    {
        char * temp = new char[until + 1];
        memset(temp, 0, until + 1);
        copy_fragment(temp, src, delim);
        if (keep_empty || *temp != 0)
        {
            if (!do_string)
            {
                Container.push_back(temp);
            }
            else
            {
                string x = temp;
                ContainerS.push_back(x);
            }

        }
        else
        {
            delete[] temp;
        }
    }
}

void StringSplit::assimilate(char*src, char* delim)
{
    int until = untilnextdelim(src, delim);
    if (until > 0)
    {
        char * temp = new char[until + 1];
        memset(temp, 0, until + 1);
        copy_fragment(temp, src, delim);
        if (keep_empty || *temp != 0)
        {
            if (!do_string)
            {
                Container.push_back(temp);
            }
            else
            {
                string x = temp;
                ContainerS.push_back(x);
            }
        }
        else
        {
            delete[] temp;
        }
    }
}

long StringSplit::calc_string_size(char* _in)
{
    long i = 0;
    while (*_in++)
    {
        i++;
    }
    return i;
}

bool StringSplit::string_contains(char* haystack, char* needle)
{
    size_t len = calc_string_size(needle);
    size_t lenh = calc_string_size(haystack);
    while (lenh--)
    {
        if (match_fragment(haystack + lenh, needle, len))
        {
            return true;
        }
    }
    return false;
}

bool StringSplit::match_fragment(char* _src, char* cmp, int len)
{
    while (len--)
    {
        if (*(_src + len) != *(cmp + len))
        {
            return false;
        }
    }
    return true;
}

int StringSplit::untilnextdelim(char* _in, char delim)
{
    size_t len = calc_string_size(_in);
    if (*_in == delim)
    {
        _in += 1;
        return len - 1;
    }

    int c = 0;
    while (*(_in + c) != delim && c < len)
    {
        c++;
    }

    return c;
}

int StringSplit::untilnextdelim(char* _in, char* delim)
{
    int s = calc_string_size(delim);
    int c = 1 + s;

    if (!string_contains(_in, delim))
    {
        return calc_string_size(_in);
    }
    else if (match_fragment(_in, delim, s))
    {
        _in += s;
        return calc_string_size(_in);
    }

    while (!match_fragment(_in + c, delim, s))
    {
        c++;
    }

    return c;
}

void StringSplit::copy_fragment(char* dest, char* src, char delim)
{
    if (*src == delim)
    {
        src++;
    }
        
    int c = 0;
    while (*(src + c) != delim && *(src + c))
    {
        *(dest + c) = *(src + c);
        c++;
    }
    *(dest + c) = 0;
}

void StringSplit::copy_string(char* dest, char* src)
{
    int i = 0;
    while (*(src + i))
    {
        *(dest + i) = *(src + i);
        i++;
    }
}

void StringSplit::copy_fragment(char* dest, char* src, char* delim)
{
    size_t len = calc_string_size(delim);
    size_t lens = calc_string_size(src);
    
    if (match_fragment(src, delim, len))
    {
        src += len;
        lens -= len;
    }
    
    int c = 0;
    while (!match_fragment(src + c, delim, len) && (c < lens))
    {
        *(dest + c) = *(src + c);
        c++;
    }
    *(dest + c) = 0;
}

vector<char*> StringSplit::split_cstr(char Delimiter)
{
    int i = 0;
    while (*String)
    {
        if (*String != Delimiter && i == 0)
        {
            assimilate(String, Delimiter);
        }
        if (*String == Delimiter)
        {
            assimilate(String, Delimiter);
        }
        i++;
        String++;
    }

    String -= i;
    delete[] String;

    return Container;
}

vector<string> StringSplit::split_string(char Delimiter)
{
    do_string = true;
    
    int i = 0;
    while (*String)
    {
        if (*String != Delimiter && i == 0)
        {
            assimilate(String, Delimiter);
        }
        if (*String == Delimiter)
        {
            assimilate(String, Delimiter);
        }
        i++;
        String++;
    }

    String -= i;
    delete[] String;

    return ContainerS;
}

vector<char*> StringSplit::split_cstr(char* Delimiter)
{
    int i = 0;
    size_t LenDelim = calc_string_size(Delimiter);

    while(*String)
    {
        if (!match_fragment(String, Delimiter, LenDelim) && i == 0)
        {
            assimilate(String, Delimiter);
        }
        if (match_fragment(String, Delimiter, LenDelim))
        {
            assimilate(String,Delimiter);
        }
        i++;
        String++;
    }

    String -= i;
    delete[] String;

    return Container;
}

vector<string> StringSplit::split_string(char* Delimiter)
{
    do_string = true;
    int i = 0;
    size_t LenDelim = calc_string_size(Delimiter);

    while (*String)
    {
        if (!match_fragment(String, Delimiter, LenDelim) && i == 0)
        {
            assimilate(String, Delimiter);
        }
        if (match_fragment(String, Delimiter, LenDelim))
        {
            assimilate(String, Delimiter);
        }
        i++;
        String++;
    }

    String -= i;
    delete[] String;

    return ContainerS;
}

Examples:

int main(int argc, char*argv[])
{
    StringSplit ss = "This:CUT:is:CUT:an:CUT:example:CUT:cstring";
    vector<char*> Split = ss.split_cstr(":CUT:");

    for (int i = 0; i < Split.size(); i++)
    {
        cout << Split[i] << endl;
    }

    return 0;
}

Will output:

This
is
an
example
cstring

int main(int argc, char*argv[])
{
    StringSplit ss = "This:is:an:example:cstring";
    vector<char*> Split = ss.split_cstr(':');

    for (int i = 0; i < Split.size(); i++)
    {
        cout << Split[i] << endl;
    }

    return 0;
}

int main(int argc, char*argv[])
{
    string mystring = "This[SPLIT]is[SPLIT]an[SPLIT]example[SPLIT]string";
    StringSplit ss = mystring;
    vector<string> Split = ss.split_string("[SPLIT]");

    for (int i = 0; i < Split.size(); i++)
    {
        cout << Split[i] << endl;
    }

    return 0;
}

int main(int argc, char*argv[])
{
    string mystring = "This|is|an|example|string";
    StringSplit ss = mystring;
    vector<string> Split = ss.split_string('|');

    for (int i = 0; i < Split.size(); i++)
    {
        cout << Split[i] << endl;
    }

    return 0;
}

To keep empty entries (by default empties will be excluded):

StringSplit ss = mystring;
ss.keep_empty = true;
vector<string> Split = ss.split_string(":DELIM:");

The goal was to make it similar to C#'s Split() method where splitting a string is as easy as:

String[] Split = 
    "Hey:cut:what's:cut:your:cut:name?".Split(new[]{":cut:"}, StringSplitOptions.None);

foreach(String X in Split)
{
    Console.Write(X);
}

I hope someone else can find this as useful as I do.

Answer 26

Here's another way of doing it..

void split_string(string text,vector<string>& words)
{
  int i=0;
  char ch;
  string word;

  while(ch=text[i++])
  {
    if (isspace(ch))
    {
      if (!word.empty())
      {
        words.push_back(word);
      }
      word = "";
    }
    else
    {
      word += ch;
    }
  }
  if (!word.empty())
  {
    words.push_back(word);
  }
}

Answer 27

Recently I had to split a camel-cased word into subwords. There are no delimiters, just upper characters.

#include <string>
#include <list>
#include <locale> // std::isupper

template<class String>
const std::list<String> split_camel_case_string(const String &s)
{
    std::list<String> R;
    String w;

    for (String::const_iterator i = s.begin(); i < s.end(); ++i) {  {
        if (std::isupper(*i)) {
            if (w.length()) {
                R.push_back(w);
                w.clear();
            }
        }
        w += *i;
    }

    if (w.length())
        R.push_back(w);
    return R;
}

For example, this splits "AQueryTrades" into "A", "Query" and "Trades". The function works with narrow and wide strings. Because it respects the current locale it splits "RaumfahrtÜberwachungsVerordnung" into "Raumfahrt", "Überwachungs" and "Verordnung".

Note std::upper should be really passed as function template argument. Then the more generalized from of this function can split at delimiters like ",", ";" or " " too.

Answer 28

What about this:

#include <string>
#include <vector>

using namespace std;

vector<string> split(string str, const char delim) {
    vector<string> v;
    string tmp;

    for(string::const_iterator i; i = str.begin(); i <= str.end(); ++i) {
        if(*i != delim && i != str.end()) {
            tmp += *i; 
        } else {
            v.push_back(tmp);
            tmp = ""; 
        }   
    }   

    return v;
}

Answer 29

I've rolled my own using strtok and used boost to split a string. The best method I have found is the C++ String Toolkit Library. It is incredibly flexible and fast.

#include <iostream>
#include <vector>
#include <string>
#include <strtk.hpp>

const char *whitespace  = " \t\r\n\f";
const char *whitespace_and_punctuation  = " \t\r\n\f;,=";

int main()
{
    {   // normal parsing of a string into a vector of strings
        std::string s("Somewhere down the road");
        std::vector<std::string> result;
        if( strtk::parse( s, whitespace, result ) )
        {
            for(size_t i = 0; i < result.size(); ++i )
                std::cout << result[i] << std::endl;
        }
    }

    {  // parsing a string into a vector of floats with other separators
        // besides spaces

        std::string s("3.0, 3.14; 4.0");
        std::vector<float> values;
        if( strtk::parse( s, whitespace_and_punctuation, values ) )
        {
            for(size_t i = 0; i < values.size(); ++i )
                std::cout << values[i] << std::endl;
        }
    }

    {  // parsing a string into specific variables

        std::string s("angle = 45; radius = 9.9");
        std::string w1, w2;
        float v1, v2;
        if( strtk::parse( s, whitespace_and_punctuation, w1, v1, w2, v2) )
        {
            std::cout << "word " << w1 << ", value " << v1 << std::endl;
            std::cout << "word " << w2 << ", value " << v2 << std::endl;
        }
    }

    return 0;
}

The toolkit has much more flexibility than this simple example shows but its utility in parsing a string into useful elements is incredible.

Answer 30

I cannot believe how overly complicated most of these answers were. Why didnt someone suggest something as simple as this?

#include <iostream>
#include <sstream>

std::string input = "This is a sentence to read";
std::istringstream ss(input);
std::string token;

while(std::getline(ss, token, ' ')) {
    std::cout << token << endl;
}