std::exception:: exception

From cppreference.com
Utilities library
General utilities
Relational operators (deprecated in C++20)
(1)
exception ( ) throw ( ) ;
(until C++11)
exception ( ) noexcept ;
(since C++11)
(constexpr since C++26)
(2)
exception ( const exception & other ) throw ( ) ;
(until C++11)
exception ( const exception & other ) noexcept ;
(since C++11)
(constexpr since C++26)

Constructs new exception object.

1) Default constructor. what() returns an implementation-defined string.
2) Copy constructor. Initializes the contents with those of other . If * this and other both have dynamic type std::exception then std:: strcmp ( what ( ) , other. what ( ) ) == 0 .

Parameters

other - another exception to assign the contents of

Notes

Because copying std::exception is not permitted to throw exceptions, when derived classes (such as std::runtime_error ) have to manage a user-defined diagnostic message, it is typically implemented as a copy-on-write string.

The Microsoft implementation includes non-standard constructors taking strings thus allowing instances to be thrown directly with a meaningful error message. The nearest standard equivalents are std::runtime_error or std::logic_error .

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 471 C++98 there is no requirement on what() of the exception copy added