I understand that a stream is a representation of a sequence of bytes. Each stream provides means for reading and writing bytes to its given backing store. But what is the point of the stream? Why isn’t the backing store itself what we interact with? For whatever reason this concept just isn’t clicking for me. … Read more
Every time I mention slow performance of C++ standard library iostreams, I get met with a wave of disbelief. Yet I have profiler results showing large amounts of time spent in iostream library code (full compiler optimizations), and switching from iostreams to OS-specific I/O APIs and custom buffer management does give an order of magnitude … Read more
I am writing a small matrix library in C++ for matrix operations. However my compiler complains, where before it did not. This code was left on a shelf for 6 months and in between I upgraded my computer from debian etch to lenny (g++ (Debian 4.3.2-1.1) 4.3.2 ) however I have the same problem on … Read more
I’m following a college course about operating systems and we’re learning how to convert from binary to hexadecimal, decimal to hexadecimal, etc. and today we just learned how signed/unsigned numbers are stored in memory using the two’s complement (~number + 1). We have a couple of exercises to do on paper and I would like … Read more
In my earlier question I was printing a double using cout that got rounded when I wasn’t expecting it. How can I make cout print a double using full precision? 16 Answers 16
What is the difference between printf() and cout in C++? 16 Answers 16 I’m surprised that everyone in this question claims that std::cout is way better than printf, even if the question just asked for differences. Now, there is a difference – std::cout is C++, and printf is C (however, you can use it in … Read more
Many C++ books contain example code like this… std::cout << “Test line” << std::endl; …so I’ve always done that too. But I’ve seen a lot of code from working developers like this instead: std::cout << “Test line\n”; Is there a technical reason to prefer one over the other, or is it just a matter of … Read more
I just found a comment in this answer saying that using iostream::eof in a loop condition is “almost certainly wrong”. I generally use something like while(cin>>n) – which I guess implicitly checks for EOF. Why is checking for eof explicitly using while (!cin.eof()) wrong? How is it different from using scanf(“…”,…)!=EOF in C (which I … Read more
I wanted to compare reading lines of string input from stdin using Python and C++ and was shocked to see my C++ code run an order of magnitude slower than the equivalent Python code. Since my C++ is rusty and I’m not yet an expert Pythonista, please tell me if I’m doing something wrong or … Read more
