std::basic_ios<CharT,Traits>::fail - cppreference.com (original) (raw)

Returns true if an error has occurred on the associated stream. Specifically, returns true if badbit or failbit is set in rdstate().

See ios_base::iostate for the list of conditions that set failbit or badbit.

[edit] Parameters

(none)

[edit] Return value

true if an error has occurred, false otherwise.

[edit] Example

#include #include #include   int main() { std::ifstream file("test.txt"); if (!file) // operator! is used here {
std::cout << "File opening failed\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 << "I/O error while reading\n"; else if (file.eof()) std::cout << "End of file reached successfully\n"; else if (file.fail()) std::cout << "Non-integer data encountered\n"; }

[edit] See also

The following table shows the value of basic_ios accessors (good(), fail(), etc.) for all possible combinations of ios_base::iostate flags: