Difference between revisions of "cpp/error/logic error"
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(Added LWG issues #254 and #471 DR (part 1/9).) |
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| − | {{cpp/title | logic_error}} | + | {{cpp/title|logic_error}} |
{{cpp/error/navbar}} | {{cpp/error/navbar}} | ||
| − | {{ddcl | header=stdexcept | | + | {{ddcl|header=stdexcept| |
class logic_error; | class logic_error; | ||
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{{cpp/error/exception/inherit}} | {{cpp/error/exception/inherit}} | ||
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| + | ===Defect reports=== | ||
| + | {{dr list begin}} | ||
| + | {{dr list item|wg=lwg|dr=254|std=C++98|before=the constructor accepting {{c|const char*}} was missing|after=added}} | ||
| + | {{dr list item|wg=lwg|dr=471|std=C++98|before=the explanatory strings of {{tt|std::logic_error}}'s<br>copies were implementation-defined|after=they are the same as that of the<br>original {{tt|std::logic_error}} object}} | ||
| + | {{dr list end}} | ||
{{langlinks|de|es|fr|it|ja|pt|ru|zh}} | {{langlinks|de|es|fr|it|ja|pt|ru|zh}} | ||
Latest revision as of 21:40, 23 October 2022
| Defined in header <stdexcept>
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| class logic_error; |
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Defines a type of object to be thrown as exception. It reports errors that are a consequence of faulty logic within the program such as violating logical preconditions or class invariants and may be preventable.
No standard library components throw this exception directly, but the exception types
std::invalid_argument, std::domain_error, std::length_error, std::out_of_range, std::future_error, and std::experimental::bad_optional_access are derived from std::logic_error.
Inheritance diagram
Contents |
[edit] Member functions
| (constructor) |
constructs a new logic_error object with the given message (public member function) |
| operator= |
replaces the logic_error object (public member function) |
std::logic_error::logic_error
| logic_error( const std::string& what_arg ); |
(1) | |
| logic_error( const char* what_arg ); |
(2) | |
| logic_error( const logic_error& other ); |
(3) | (noexcept since C++11) |
std::logic_error then std::strcmp(what(), other.what()) == 0. No exception can be thrown from the copy constructor.Parameters
| what_arg | - | explanatory string |
| other | - | another exception object to copy |
Exceptions
Notes
Because copying std::logic_error is not permitted to throw exceptions, this message is typically stored internally as a separately-allocated reference-counted string. This is also why there is no constructor taking std::string&&: it would have to copy the content anyway.
Before the resolution of LWG issue 254, the non-copy constructor can only accept std::string. It makes dynamic allocation mandatory in order to construct a std::string object.
After the resolution of LWG issue 471, a derived standard exception class must have a publicly accessible copy constructor. It can be implicitly defined as long as the explanatory strings obtained by what() are the same for the original object and the copied object.
std::logic_error::operator=
| logic_error& operator=( const logic_error& other ); |
(noexcept since C++11) | |
Assigns the contents with those of other. If *this and other both have dynamic type std::logic_error then std::strcmp(what(), other.what()) == 0 after assignment. No exception can be thrown from the copy assignment operator.
Parameters
| other | - | another exception object to assign with |
Return value
*this
Notes
After the resolution of LWG issue 471, a derived standard exception class must have a publicly accessible copy assignment operator. It can be implicitly defined as long as the explanatory strings obtained by what() are the same for the original object and the copied object.
Inherited from std::exception
Member functions
| [virtual] |
destroys the exception object (virtual public member function of std::exception)
|
| [virtual] |
returns an explanatory string (virtual public member function of std::exception)
|
[edit] Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 254 | C++98 | the constructor accepting const char* was missing | added |
| LWG 471 | C++98 | the explanatory strings of std::logic_error'scopies were implementation-defined |
they are the same as that of the original std::logic_error object
|
