std::logic_error
(C++17)<stdexcept>
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.
std::logic_error are constexpr: it is possible to create and use std::logic_error objects in the evaluation of a constant expression.However, std::logic_error objects generally cannot be constexpr, because any dynamically allocated storage must be released in the same evaluation of constant expression.
Inheritance diagram
Contents
[edit] Member functions
logic_error object with the given message (public member function)
logic_error object (public member function)
std::logic_error::logic_error
(constexpr since C++26)
std::logic_error then std::strcmp (what(), other.what()) == 0. No exception can be thrown from the copy constructor.Parameters
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=
(constexpr since C++26)
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
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
[edit] Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_constexpr_exceptions |
202502L |
(C++26) | constexpr exception types |
[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
|