std::system_error

 

C++

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Language support library

Concepts library (C++20)

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Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)
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rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
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strong_order weak_order partial_order strong_equal weak_equal	strong_ordering weak_ordering partial_ordering strong_equality weak_equality	is_eqis_neqis_ltis_lteqis_gtis_gteq
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pair tuple (C++11) apply (C++17) make_from_tuple (C++17)	optional (C++17) any (C++17) variant (C++17)
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Error handling

Exception handling exception uncaught_exceptionuncaught_exceptions (C++17) exception_ptr (C++11) make_exception_ptr (C++11) current_exception (C++11) rethrow_exception (C++11) nested_exception (C++11) throw_with_nested (C++11) rethrow_if_nested (C++11) Exception handling failures terminate terminate_handler get_terminate (C++11) set_terminate bad_exception unexpected (until C++17) unexpected_handler (until C++17) get_unexpected (C++11)(until C++17) set_unexpected (until C++17) Contracts contract_violation (C++20)

Exception categories logic_error invalid_argument domain_error length_error out_of_range runtime_error range_error overflow_error underflow_error tx_exception (TM TS) Error codes Error codes errno Assertions assert system_error facility error_category (C++11) generic_category (C++11) system_category (C++11) error_condition (C++11) errc (C++11) error_code (C++11) system_error (C++11)

 

Defined in header <system_error>
class system_error;		(since C++11)

std::system_error is the type of the exception thrown by various library functions (typically the functions that interface with the OS facilities, e.g. the constructor of std::thread) when the exception has an associated std::error_code, which may be reported.

Inheritance diagram

Member functions

(constructor)	constructs the system_error object (public member function)
code	returns error code (public member function)
what [virtual]	returns explanatory string (virtual public member function)

Inherited from std::exception

Member functions

(destructor) [virtual]	destroys the exception object (virtual public member function of std::exception)
what [virtual]	returns an explanatory string (virtual public member function of std::exception)

Example

Run this code

#include <thread>
#include <iostream>
#include <system_error>
 
int main()
{
    try {
        std::thread().detach(); // attempt to detach a non-thread
    } catch(const std::system_error& e) {
        std::cout << "Caught system_error with code " << e.code() 
                  << " meaning " << e.what() << '\n';
    }
}

Output:

Caught system_error with code generic:22 meaning Invalid argument