std::numpunct<CharT>::grouping, std::numpunct<CharT>::do_grouping
Defined in header <locale>
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public: std::string grouping() const; |
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protected: virtual std::string do_grouping() const; |
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do_grouping
of the most derived class.This function returns a string, vec, which is used as a vector of integer values. (For example, "\003" specifies groups of 3 digits each, while "3" implies groups of 51 digits each.). Each element vec[i] represents the number of digits in the i
th digit group of the integer part of the number, counting from the right: vec[0] holds the number of digits in the rightmost group, vec[1] - in the second group from the right, etc. The grouping indicated by the last character, vec[vec.size()-1], is repeatedly reused to group all remaining digits in the (left part of) the number. If vec[i] is non-positive or equals CHAR_MAX the size of the corresponding digit group is unlimited.
[edit] Return value
The object of type std::string holding the groups. The standard specializations of std::numpunct
return an empty string, indicating no grouping. Typical groupings (e.g. the en_US
locale) return "\003".
[edit] Example
#include <iostream> #include <limits> #include <locale> struct space_out : std::numpunct<char> { char do_thousands_sep() const { return ' '; } // separate with spaces std::string do_grouping() const { return "\1"; } // groups of 1 digit }; struct g123 : std::numpunct<char> { std::string do_grouping() const { return "\1\2\3"; } }; int main() { std::cout << "Default locale: " << 12345678 << '\n'; std::cout.imbue(std::locale(std::cout.getloc(), new space_out)); std::cout << "Locale with modified numpunct: " << 12345678 << '\n'; std::cout.imbue(std::locale(std::cout.getloc(), new g123)); std::cout << "Locale with \\1\\2\\3 grouping: " << std::numeric_limits<unsigned long long>::max() << '\n' << "Same, for a floating-point number: " << std::fixed << 123456789.123456789 << '\n'; }
Output:
Default locale: 12345678 Locale with modified numpunct: 1 2 3 4 5 6 7 8 Locale with \1\2\3 grouping: 18,446,744,073,709,551,61,5 Same, for a floating-point number: 123,456,78,9.123457
[edit] See also
[virtual] |
provides the character to use as thousands separator (virtual protected member function) |