ostream

问题 Is there a way to set the "minimum" number of decimal places that a std::ostream will output? For example, say I have two unknown double variables that I want to print (values added here for the sake of illustration): double a = 0; double b = 0.123456789; I can set my maximum decimal precision so that I output b exactly std::cout << std::setprecision(9) << b << std::endl; >>> 0.123456789 Is there a way to set a "minimum" precision (a minimum number of decimal places), while retaining the

问题 Is there a way to set the "minimum" number of decimal places that a std::ostream will output? For example, say I have two unknown double variables that I want to print (values added here for the sake of illustration): double a = 0; double b = 0.123456789; I can set my maximum decimal precision so that I output b exactly std::cout << std::setprecision(9) << b << std::endl; >>> 0.123456789 Is there a way to set a "minimum" precision (a minimum number of decimal places), while retaining the

问题 Please consider the following code. I'm trying to output a vector of vectors to an ostream. #include <iterator> #include <iostream> #include <string> #include <vector> #include <algorithm> template<typename T> std::ostream &operator <<(std::ostream &os, const std::vector<T> &v) { using namespace std; copy(v.begin(), v.end(), ostream_iterator<T>(os, "\n")); return os; } int main() { using namespace std; vector<string> v1; cout << v1; vector<vector<string> > v2; cout << v2; return 0; } The

问题 Please consider the following code. I'm trying to output a vector of vectors to an ostream. #include <iterator> #include <iostream> #include <string> #include <vector> #include <algorithm> template<typename T> std::ostream &operator <<(std::ostream &os, const std::vector<T> &v) { using namespace std; copy(v.begin(), v.end(), ostream_iterator<T>(os, "\n")); return os; } int main() { using namespace std; vector<string> v1; cout << v1; vector<vector<string> > v2; cout << v2; return 0; } The

问题 Please consider the following code. I'm trying to output a vector of vectors to an ostream. #include <iterator> #include <iostream> #include <string> #include <vector> #include <algorithm> template<typename T> std::ostream &operator <<(std::ostream &os, const std::vector<T> &v) { using namespace std; copy(v.begin(), v.end(), ostream_iterator<T>(os, "\n")); return os; } int main() { using namespace std; vector<string> v1; cout << v1; vector<vector<string> > v2; cout << v2; return 0; } The

问题 Please consider the following code. I'm trying to output a vector of vectors to an ostream. #include <iterator> #include <iostream> #include <string> #include <vector> #include <algorithm> template<typename T> std::ostream &operator <<(std::ostream &os, const std::vector<T> &v) { using namespace std; copy(v.begin(), v.end(), ostream_iterator<T>(os, "\n")); return os; } int main() { using namespace std; vector<string> v1; cout << v1; vector<vector<string> > v2; cout << v2; return 0; } The

来源： https://stackoverflow.com/questions/45172025/about-stdostream-constructor

来源： https://stackoverflow.com/questions/61447637/you-don-t-have-permission-to-write-to-the-folder-that-the-file-ostream-is-in

来源： https://stackoverflow.com/questions/61447637/you-don-t-have-permission-to-write-to-the-folder-that-the-file-ostream-is-in

问题 I'm trying to understand this code istream &read(istream &is, Sales_data &item) { double price = 0; is >> item.bookNo >> item.units_sold >> price; item.revenue = price * item.units_sold; return is; } ostream &print(ostream &os, const Sales_data &item) { os << item.isbn() << " " << item.units_sold << " " << item.revenue << " " << item.avg_price(); return os; } I don't understand what are these function , also I can't understand why we use istream for reading and ostream for printing instead of