How do I deal with the max macro in windows.h colliding with max in std?
Define the macro NOMINMAX: This will suppress the min and max definitions in Windef.h.
iostream
‘cout’ was not declared in this scope [closed]
Put the following code before int main(): using namespace std; And you will be able to use cout. For example: #include<iostream> using namespace std; int main(){ char t=”f”; char *t1; char **t2; cout<<t; return 0; } Now take a moment and read up on what cout is and what is going on here: http://www.cplusplus.com/reference/iostream/cout/ Further, … Read more
Big difference (x9) in the execution time between almost identical code in C and C++
Both programs do exactly the same thing. They use the same exact algorithm, and given its low complexity, their performance is mostly bound to efficiency of the input and output handling. scanning the input with scanf(“%d”, &fact_num); on one side and cin >> fact_num; on the other does not seem very costly either way. In … Read more
What exactly is streambuf? How do I use it?
With the help of streambuf, we can work in an even lower level. It allows access to the underlying buffers. Here are some good examples : Copy, load, redirect and tee using C++ streambufs and in reference to comparison, This might be helpful, See this for more details : IOstream Library
How to read a file line by line or a whole text file at once?
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
How to read until EOF from cin in C++
The only way you can read a variable amount of data from stdin is using loops. I’ve always found that the std::getline() function works very well: std::string line; while (std::getline(std::cin, line)) { std::cout << line << std::endl; } By default getline() reads until a newline. You can specify an alternative termination character, but EOF is … Read more
operator
The problem is that you define it inside the class, which a) means the second argument is implicit (this) and b) it will not do what you want it do, namely extend std::ostream. You have to define it as a free function: class A { /* … */ }; std::ostream& operator<<(std::ostream&, const A& a);
Why would we call cin.clear() and cin.ignore() after reading input?
The cin.clear() clears the error flag on cin (so that future I/O operations will work correctly), and then cin.ignore(10000, ‘\n’) skips to the next newline (to ignore anything else on the same line as the non-number so that it does not cause another parse failure). It will only skip up to 10000 characters, so the … Read more
Reading from text file until EOF repeats last line [duplicate]
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
Who architected / designed C++’s IOStreams, and would it still be considered well-designed by today’s standards? [closed]
Regarding who designed them, the original library was (not surprisingly) created by Bjarne Stroustrup, and then reimplemented by Dave Presotto. This was then redesigned and reimplemented yet again by Jerry Schwarz for Cfront 2.0, using the idea of manipulators from Andrew Koenig. The standard version of the library is based on this implementation. Source “The … Read more