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std::basic_...am::is_open(3) C++ Standard Libary std::basic_...am::is_open(3) NAME std::basic_ifstream::is_open - std::basic_ifstream::is_open Synopsis bool is_open() const; Checks if the file stream has an associated file. Effectively calls rdbuf()->is_open(). Parameters (none) Return value true if the file stream has an associated file, false otherwise. Example // Run this code #include <fstream> #include <iostream> #include <string> // this file is called main.cpp bool file_exists(const std::string& str) { std::ifstream fs(str); return fs.is_open(); } int main() { std::boolalpha(std::cout); std::cout << file_exists("main.cpp") << '\n' << file_exists("strange_file") << '\n'; } Possible output: true false Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Correct behavior LWG 365 C++98 is_open was not declared with const qualifier de- clared with const qual- ifier See also open opens a file and associates it with the stream (public member function) close closes the associated file (public member function) http://cppreference.com 2024.06.10 std::basic_...am::is_open(3)
NAME | Synopsis | Parameters | Return value | Example | Possible output: | See also
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