Splitting a C++ std::string using tokens, e.g. ";"

Question

Possible Duplicate:
How to split a string in C++?

Best way to split a string in C++? The string can be assumed to be composed of words separated by ;

From our guide lines point of view C string functions are not allowed and also Boost is also not allowed to use because of security conecerns open source is not allowed.

The best solution I have right now is:

string str("denmark;sweden;india;us");

Above str should be stored in vector as strings. how can we achieve this?

Thanks for inputs.

I don't think this should be marked as a duplicate, the other question promotes elegance over efficiency, which I disagree with and avoided for that very reason. — user2462027, Dec 12 '14 at 07:51
"[HOW TO SPLIT A STRING IN C++](http://www.martinbroadhurst.com/how-to-split-a-string-in-c.html)" lists few nice alternatives. — Petr Vepřek, Aug 17 '18 at 10:32

Martin Stone · Accepted Answer · 2018-06-25T09:21:01.210

252

I find std::getline() is often the simplest. The optional delimiter parameter means it's not just for reading "lines":

#include <sstream>
#include <iostream>
#include <vector>

using namespace std;

int main() {
    vector<string> strings;
    istringstream f("denmark;sweden;india;us");
    string s;    
    while (getline(f, s, ';')) {
        cout << s << endl;
        strings.push_back(s);
    }
}

edited Jun 25 '18 at 09:21

answered Mar 02 '11 at 12:58

Martin Stone

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12

Great method! Write carefully though. At first I couldn't compile this ... because I had been using double quotes on the delimiter (getline(f, s, ";")). #FeelingStupid. – Francis Pierot Jun 14 '17 at 13:02
Any idea how to split string based on another string? For example, split `"abdecfdcfe"` by the string `"de"` which will return `{"ab", "cfdcfe"}`. Also any way to split string for multiple characters? Like in the above example, the answer will be `{"ab", "cf", "cf"}`. – Rahat Zaman Apr 26 '20 at 00:49
Using for-loop as in `for (string s; getline(f, s, ';'); )` is also nice. – yugr Feb 27 '23 at 19:42

score 22 · Answer 2 · edited May 23 '17 at 12:02

22

You could use a string stream and read the elements into the vector.

Here are many different examples...

A copy of one of the examples:

std::vector<std::string> split(const std::string& s, char seperator)
{
   std::vector<std::string> output;

    std::string::size_type prev_pos = 0, pos = 0;

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

        output.push_back(substring);

        prev_pos = ++pos;
    }

    output.push_back(s.substr(prev_pos, pos-prev_pos)); // Last word

    return output;
}

edited May 23 '17 at 12:02

Community

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answered Mar 02 '11 at 12:44

Fox32

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in the link provided space is used as a seperator how can i specify";" as a seperator – venkysmarty Mar 02 '11 at 12:48
1

There are many exampels, some with space seperator and some with a variable seperator – Fox32 Mar 02 '11 at 12:49
More examples can be found in this question. http://stackoverflow.com/q/53849/2298 – KeithB Mar 02 '11 at 13:27
1

Accept strings into functions by ref-to-const please! – Lightness Races in Orbit Mar 02 '11 at 13:50
Oh, and it's spelt "examples" ;) – Lightness Races in Orbit Mar 02 '11 at 13:51

score 11 · Answer 3 · answered Mar 02 '11 at 14:16

There are several libraries available solving this problem, but the simplest is probably to use Boost Tokenizer:

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

typedef boost::tokenizer<boost::char_separator<char> > tokenizer;

std::string str("denmark;sweden;india;us");
boost::char_separator<char> sep(";");
tokenizer tokens(str, sep);

BOOST_FOREACH(std::string const& token, tokens)
{
    std::cout << "<" << *tok_iter << "> " << "\n";
}

Splitting a C++ std::string using tokens, e.g. ";"

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