- Microsoft dropped the ball... - 3 Updates
| Juha Nieminen <nospam@thanks.invalid>: Sep 18 07:41PM > I thought we were talking about formatted output, that's what fprintf() > and streams are all about. I'm curious, how many times have you used > std::ostream::write() in your operator<< ? My point is that in the implementation of the operator<<() overload for your custom type you can use std::ostream::write() to output the value you want if you so want. Or any of the other functions that std::ostream offers. (In some cases the write() function could actually be the *simplest* way of outputing the value. It's also probably the most efficient, as a bonus.) You don't have that option in the scenario you suggested. > Also, I consider it a good thing to modularize the program. Why should > the code formatting the object content know or care about streams or > FILE* pointers? For optimization reasons. And it's not like a stream-aware printing function and a generic print-to-string function are mutually exclusive. >> Also, somewhat ironically, in some cases you would need to resort to >> stringstreams in order to create the string to be printed. > So what? This is an implementation detail. I just said it's a bit ironic. > How comes? If everything supports conversion to strings, it's trivial to > use in templates. Since C++11 we also have std::to_string() for > primitive types, so they could be easily incorporated as well if needed. std::to_string() does not support *any* formatting parameters (such as printing in hex, or with a minimum width, with or without leading characters, or the different types of floating point formats, and so on.) It also doesn't support all primitive types, most particularly pointers. With std::ostream using formatting parameters may not be as handy as with std::printf(), but at least the possibility is there. |
| Juha Nieminen <nospam@thanks.invalid>: Sep 18 07:45PM > Isn't it that printf can be now implemented in type safe manner? Not exactly printf, but a very printf-like function yes, indeed. https://en.cppreference.com/w/cpp/utility/format |
| Paavo Helde <eesnimi@osa.pri.ee>: Sep 19 12:40AM +0300 18.09.2020 22:41 Juha Nieminen kirjutas: > std::ostream offers. (In some cases the write() function could > actually be the *simplest* way of outputing the value. It's also > probably the most efficient, as a bonus.) Well, I find it ironic that you bring up efficiency in the context of iostreams, which are for sure the most inefficient way to output something from a C++ program. Efficiency is not always the most dominant concern, but when it is you can bet iostreams are not the solution you are looking for. Just do a little benchmark and measure string concatenation speed with stringstream << vs std::string +=. Granted, std::string+= does not do things like locale support, but when you are concerned about the speed of output it means no human will look at the output and therefore no locale-specific behavior is needed or wanted. |
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