std::basic_ios<CharT,Traits>::eof
Returns true if the associated stream has reached end-of-file. Specifically, returns true if eofbit
is set in rdstate() .
See ios_base::iostate for the list of conditions that set eofbit
.
Contents
[edit] Parameters
(none)
[edit] Return value
true if an end-of-file has occurred, false otherwise.
[edit] Notes
This function only reports the stream state as set by the most recent I/O operation; it does not examine the associated data source. For example, if the most recent I/O was a get() which returned the last byte of a file, eof()
returns false. The next get()
fails to read anything and sets the eofbit
. Only then does eof()
return true.
In typical usage, input stream processing stops on any error. eof()
and fail() can then be used to distinguish between different error conditions.
[edit] Example
#include <cstdlib> #include <fstream> #include <iostream> 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:
basic_ios
accessors