The short answer is no. The reason, is because the std::fstream is not required to use a FILE* as part of its implementation. So even if you manage to extract file descriptor from the std::fstream object and manually build a FILE object, then you will have other problems because you will now have two buffered … Read more
It’s the other way around. When ios::ate is set, the initial position will be the end of the file, but you are free to seek thereafter. When ios::app is set, all output operations are performed at the end of the file. Since all writes are implicitly preceded by seeks, there is no way to write … Read more
You can use std::getline : #include <fstream> #include <string> int main() { std::ifstream file(“Read.txt”); std::string str; while (std::getline(file, str)) { // Process str } } Also note that it’s better you just construct the file stream with the file names in it’s constructor rather than explicitly opening (same goes for closing, just let the destructor … Read more
From the answer given by Éric Malenfant: AFAIK, there is no way to do this in standard C++. Depending on your platform, your implementation of the standard library may offer (as a nonstandard extension) a fstream constructor taking a file descriptor as input. (This is the case for libstdc++, IIRC) or a FILE*. Based on … Read more
Just follow closely the chain of events. Grab 10 Grab 20 Grab 30 Grab EOF Look at the second-to-last iteration. You grabbed 30, then carried on to check for EOF. You haven’t reached EOF because the EOF mark hasn’t been read yet (“binarically” speaking, its conceptual location is just after the 30 line). Therefore you … Read more
This seems to be answered – #include <fstream>. The message means :- incomplete type – the class has not been defined with a full class. The compiler has seen statements such as class ifstream; which allow it to understand that a class exists, but does not know how much memory the class takes up. The … Read more
I was trying to find the final word on mmap / read performance on Linux and I came across a nice post (link) on the Linux kernel mailing list. It’s from 2000, so there have been many improvements to IO and virtual memory in the kernel since then, but it nicely explains the reason why … Read more