iostream

This code: #include <iostream> #include <cstdio> #include <fstream> #include <string> int main() { std::remove("test.txt"); std::fstream f("test.txt",std::ios::in | std::ios::out | std::ios::binary | std::ios::trunc); std::cout << f.good() << std::endl; f<<"test"<< std::flush; std::cout << f.tellg() << " " << f.tellp() << std::endl; f.seekg(0); std::string s; f>>s; std::cout << f.tellg() << " " << f.tellp() << std::endl; } Gives following output in gcc-4.4.5 1 4 4 4 4 i.e. both tellg and tellp returned expected stream position 4. While gcc-4.6.0 Gives: 1 4 4 -1 4 Where can I find a reference

How can I derive my own stream from a standard stream? In C# language, there is a Stream class, but C++'s streams are too complex. I want something like this: class my_stream : public std::stream { // How to derive? }; void using_a_stream(std::stream* s) { *s << "Hello world"; } void main() { std::stream s1; std::fstream s2("C:\\test.txt"); my_stream s3; using_a_stream(&s1); using_a_stream(&s2); using_a_stream(&s3); } Note: The code just a sample and may be invalid C++ program. Thanks. I think there are three levels of answer to this question: Level 1 : It is complicated, especially if you are

This question already has an answer here: iostream vs ostream what is different? 5 answers I've noticed that many people include iostream and ostream in C++ programs separately, like so: #include <iostream> #include <ostream> int main() { } Why would anyone do that? Since iostream inherits from ostream, it should include everything in it, right? Is there some obscure reason? What about simple (std::cout) code? Although stringstream inherits from iostream , it is not declared in the <iostream> header. The <iostream> header contains the definition of the iostream type along with the famous cout

I just came across this question which is about how to be able to print an object via std::cout << x << std::endl; As I understood, the standard way to accomplish this is to overload the ostreams << operator. However, this is adding a feature to the ostream rather than to my class. The alternative (also given as answer to the above mentioned question) is to override the string conversion operator. However, this comes with the warning of leading to "unintentional conversions and hard-to-trace bugs". Now i wonder if there are any drawbacks of writing a toString() method and then using it via std

I want a ostream with a prefix at the beginning of every line redirected on cout; I try this: #include <iostream> #include <thread> class parallel_cout : public std::ostream { public: parallel_cout(std::ostream& o):out(o){} template <typename T> std::ostream& operator<< (const T& val) { out << "prefix " << val; return *this; } std::ostream& out; }; int main() { parallel_cout pc(std::cout); pc<<"a\nb"<<"c\n"; } but i have in output prefix a b without c. why this? The way you modify the behavior of std::ostream is not by overloading any of the output operators! Instead, you derive a class from