bool bad() const; |
Returns true
if non-recoverable error has occurred on the associated stream. Specifically, returns true
if badbit
is set in rdstate()
.
See ios_base::iostate
for the list of conditions that set badbit
.
(none).
true
if a non-recoverable error has occurred, false
otherwise.
#include <iostream> #include <fstream> #include <cstdlib> 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"; }
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 |
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