PyCharm is lying to you. The source code you’re looking at is a fake that PyCharm has created. PyCharm knows what functions should be there, and it can guess at their signatures using the function docstrings, but it has no idea what the function bodies should look like. If you want to see the real … Read more
Here is what I have gathered so far: Buffering: If by default the buffer is very small, increasing the buffer size can definitely improve the performance: it reduces the number of HDD hits it reduces the number of system calls Buffer can be set by accessing the underlying streambuf implementation. char Buffer[N]; std::ifstream file(“file.txt”); file.rdbuf()->pubsetbuf(Buffer, … Read more
Short answer No. Explanation [namespace.std] says: Let F denote a standard library function ([global.functions]), a standard library static member function, or an instantiation of a standard library function template. Unless F is designated an addressable function, the behavior of a C++ program is unspecified (possibly ill-formed) if it explicitly or implicitly attempts to form a … Read more
This is implementation dependent: Standard 23.1.2.8: The insert members shall not affect the validity of iterators and references to the container, and the erase members shall invalidate only iterators and references to the erased elements. Maybe you could try this — this is standard conforming: for (auto it = numbers.begin(); it != numbers.end(); ) { … Read more
I decided to test the solutions by dman and Charles Bailey here. I’ll call them solutions A and B respectively. My test is visiting each combination of of a vector<int> size = 100, 5 at a time. Here’s the test code: Test Code struct F { unsigned long long count_; F() : count_(0) {} bool … Read more
Here’s a sequence pseudo-container I pieced together from § 23.2.1\4 Note that the iterator_category should be one of std::input_iterator_tag, std::output_iterator_tag,std::forward_iterator_tag,std::bidirectional_iterator_tag,std::random_access_iterator_tag. Also note that the below is technically more strict than required, but this is the idea. Note that the vast majority of the “standard” functions are technically optional, due to the awesomeness that is iterators. … Read more
The libc++ basic_string is designed to have a sizeof 3 words on all architectures, where sizeof(word) == sizeof(void*). You have correctly dissected the long/short flag, and the size field in the short form. what value would __min_cap, the capacity of short strings, take for different architectures? In the short form, there are 3 words to … Read more
Modern C++ makes this super simple. C++20 C++20 introduces std::format, which allows you to do exactly that. It uses replacement fields similar to those in python: #include <iostream> #include <format> int main() { std::cout << std::format(“Hello {}!\n”, “world”); } Code from cppreference.com, CC BY-SA and GFDL Check out the compiler support page to see if it’s … Read more
Adapted from Not So Frequently Asked Questions: #include <algorithm> #include <cctype> #include <string> std::string data = “Abc”; std::transform(data.begin(), data.end(), data.begin(), [](unsigned char c){ return std::tolower(c); }); You’re really not going to get away without iterating through each character. There’s no way to know whether the character is lowercase or uppercase otherwise. If you really hate … Read more
Here is what may be happening here. You should be able to confirm this by looking at your compiler’s implementation of the pow function: Assuming you have the correct #include’s, (all the previous answers and comments about this are correct — don’t take the #include files for granted), the prototype for the standard pow function … Read more