string grouping() const;
basic_string<char>) where each
charelement shall be interpreted as an integer value indicating the number of digits in each group. Grouping is considered from right to left, with the first character in the string being used for the rightmost group, and the last character used for any group farther away than the length of the string.
"\03"indicates groups of three digits each, while
"\02\03"would indicate that the rightmost group has two digits and all the remaining ones have three digits each.
"C"locale: an empty string, indicating no grouping.
basic_string<char>no matter what character type is used as template parameter charT.
one million: 1,000,000