How can I set the decimal separator to be a comma?
I would like to read and write pi as 3,141592 instead of 3.141592 , as using the comma is common in many European countries. How can I accomplish this with iostream s? In other words cout << 3.141592; should print 3,141592 to standard output. You should use basic_ios::imbue to set the preferred locale. Take a look here: http://www.cplusplus.com/reference/ios/ios_base/imbue/ Locales allow you to use the preferred way by the user, so if a computer in Italy uses comma to separate decimal digits, in the US the dot is still used. Using locales is a Good Practice. But if you want to explicitly force