Count words in a string

Question

I need som help with counting words in a string s. count the number of words in a string s. Words are separated by whitespace. Has a sol

istringstream iss(s);
st         


        

Answer 1

You can use getline with character delimiter.

istream& std::getline (istream& is, string& str, char delim);

Something like:

std::replace_if(s.begin(), s.end(), isColon, ';');
istringstream iss(s);
string temp;
int words = 0;
while (std::getline(iss,temp,';') {
  ++words;
}

And the predicate:

bool isColon (char c) { return (c == ';'); }

Answer 2

Some simple hand crafted loops:

#include <cctype>
#include <iostream>

int main() {
    unsigned result = 0;
    std::string s = "Hello world";
    std::string::const_iterator c = s.begin();
    while(c != s.end() && std::isspace(*c)) ++c;
    while(c != s.end() && ! std::isspace(*c)) {
        ++result;
        while(++c != s.end() &&  ! std::isspace(*c));
        if(c != s.end()) {
            while(std::isspace(*c)) ++c;
        }
    }
    std::cout << "Words in '" << s << "': " << result << '\n';
}

Answer 3

It is also possible to use regular expressions:

   std::regex rx("(\\w+)(;|,)*");
   std::string text = "this;is,a;test";

   auto words_begin = std::sregex_iterator(text.begin(), text.end(), rx);
   auto words_end = std::sregex_iterator();

   auto count = std::distance(words_begin, words_end);

   std::cout << "count: " << count << std::endl;

   for(auto i = words_begin; i != words_end; ++i)
   {
      auto match = *i;
      std::cout << match[1] << '\n';
   }

The output is:

count: 4
this
is
a
test