| I/O manipulators | ||||
| Print functions(C++23) | ||||
| C-style I/O | ||||
| Buffers | ||||
(C++23) | ||||
(C++98/26*) | ||||
(C++20) | ||||
| Streams | ||||
| Abstractions | ||||
| File I/O | ||||
| String I/O | ||||
| Array I/O | ||||
(C++23) | ||||
(C++23) | ||||
(C++23) | ||||
(C++98/26*) | ||||
(C++98/26*) | ||||
(C++98/26*) | ||||
| Synchronized Output | ||||
(C++20) | ||||
| Types | ||||
| Error category interface | ||||
iostream_category (C++11) | ||||
(C++11) |
Defined in header <ios> | ||
conststd::error_category& iostream_category()noexcept; | (since C++11) | |
Obtains a reference to the static error category object for iostream errors. The object is required to override the virtual functionerror_category::name() to return a pointer to the string"iostream". It is used to identify error codes provided in the exceptions of typestd::ios_base::failure.
Contents |
(none)
A reference to the static object of unspecified runtime type, derived fromstd::error_category.
#include <fstream>#include <iostream> int main(){std::ifstream f("doesn't exist");try{ f.exceptions(f.failbit);}catch(conststd::ios_base::failure& e){std::cout<<"Caught an ios_base::failure.\n"<<"Error code: "<< e.code().value()<<" ("<< e.code().message()<<")\n"<<"Error category: "<< e.code().category().name()<<'\n'; }}
Possible output:
Caught an ios_base::failure.Error code: 1 (unspecified iostream_category error)Error category: iostream
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2087 | C++11 | iostream_category was not declarednoexcept | declarednoexcept |
| stream exception (public member class of std::ios_base)[edit] | |
(C++11) | the IO stream error codes (enum)[edit] |
