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std::basic_ios::good(3) C++ Standard Libary std::basic_ios::good(3) NAME std::basic_ios::good - std::basic_ios::good Synopsis bool good() const; Returns true if the most recent I/O operation on the stream com- pleted successfully. Specifically, returns result of rdstate() == 0. See ios_base::iostate for the list of conditions that set the stream status bits. Parameters (none) Return value true if the stream error flags are all false, false otherwise. Example // Run this code #include <iostream> #include <fstream> #include <cstdlib> int main() { const char* fname = "/tmp/test.txt"; std::ofstream ofile{fname}; ofile << "10 " << "11 " << "12 " << "non-int"; ofile.close(); std::ifstream file{fname}; if (!file.good()) { std::cout << "#1. Opening file test.txt failed - " "one of the error flags is true\n"; return EXIT_FAILURE; } // typical C++ I/O loop uses the return value of the I/O function // as the loop controlling condition, operator bool() is used here for (int n; file >> n; ) { std::cout << n << ' '; } std::cout << '\n'; if (file.bad()) { std::cout << "#2. I/O error while reading - badbit is true\n"; return EXIT_FAILURE; } else if (file.eof()) { std::cout << "#3. End of file reached successfully - eofbit is true\n" "This is fine even though file.good() is false\n"; } else if (file.fail()) { std::cout << "#4. Non-integer data encountered - failbit is true\n"; } } Possible output: 10 11 12 #4. Non-integer data encountered - failbit is true See also The following table shows the value of basic_ios accessors (good(), fail(), etc.) for all possible combinations of ios_base::iostate flags: ios_base::iostate flags basic_ios accessors eofbit failbit badbit good() fail() bad() eof() operator bool operator! false false false true false false false true false false false true false true true false false true false true false false true false false false true false true true false true true false false true true false false false false false true true false true false true false true true true false true true true false false true false true false true true true true false true true true false true http://cppreference.com 2022.07.31 std::basic_ios::good(3)
NAME | Synopsis | Parameters | Return value | Example | Possible output: | See also
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