#include <cstddef>#include <iostream>#include <locale>#include <sstream>#include <vector> // This ctype facet classifies commas and endlines as whitespacestruct csv_whitespace:std::ctype<char>{staticconst mask* make_table(){// make a copy of the "C" locale tablestaticstd::vector<mask> v(classic_table(), classic_table()+ table_size);        v[',']|=  space;// comma will be classified as whitespace        v[' ']&= ~space;// space will not be classified as whitespacereturn&v[0];}     csv_whitespace(std::size_t refs=0): ctype(make_table(),false, refs){}}; int main(){std::string in="Column 1,Column 2,Column 3\n123,456,789";std::string token; std::cout<<"Default locale:\n";std::istringstream s1(in);while(s1>> token)std::cout<<"  "<< token<<'\n'; std::cout<<"Locale with modified ctype:\n";std::istringstream s2(in);    s2.imbue(std::locale(s2.getloc(), new csv_whitespace));while(s2>> token)std::cout<<"  "<< token<<'\n';}

Default locale:  Column  1,Column  2,Column  3  123,456,789Locale with modified ctype:  Column 1  Column 2  Column 3  123  456  789