std::system_error::system_error

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)
Dynamic memory management
Error handling
Program utilities
Variadic functions
Library feature-test macros
Date and time
Function objects
initializer_list (C++11)
bitset
hash (C++11)
integer_sequence (C++14)
Relational operators (deprecated in C++20)
rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
Comparisons (C++20)
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
common_comparison_category
Common vocabulary types
pair tuple (C++11) apply (C++17) make_from_tuple (C++17)	optional (C++17) any (C++17) variant (C++17)
Swap, forward and move
swap
exchange (C++14)
forward (C++11)
move (C++11)
move_if_noexcept (C++11)
Elementary string conversions
to_chars (C++17)
from_chars (C++17)
chars_format (C++17)
Type operations
declval (C++11)
as_const (C++17)
launder (C++17)

 

Error handling

Exception handling exception uncaught_exceptionuncaught_exceptions (until C++20)(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)

 

std::system_error

Member functions

system_error::system_error

system_error::code

system_error::what

 

system_error( std::error_code ec );	(1)	(since C++11)
system_error( std::error_code ec, const std::string& what_arg );	(2)	(since C++11)
system_error( std::error_code ec, const char* what_arg );	(2)	(since C++11)
system_error( int ev, const std::error_category& ecat );	(3)	(since C++11)
system_error( int ev, const std::error_category& ecat,               const std::string& what_arg);	(4)	(since C++11)
system_error( int ev, const std::error_category& ecat,               const char* what_arg);	(4)	(since C++11)

Constructs new system error object.

1) Constructs with error code ec

2) Constructs with error code ec and explanation string what_arg. The string returned by what() is guaranteed to contain what_arg as a substring.

3) Constructs with underlying error code ev and associated error category ecat.

4) Constructs with underlying error code ev, associated error category ecat and explanatory string what_arg. The string returned by what() is guaranteed to contain what_arg as a substring.

Parameters

ec	-	error code
ev	-	underlying error code in the enumeration associated with ecat
ecat	-	the category of error
what_arg	-	explanatory string

Example

Demonstrates how to create a system_error exception from an errno value.

Run this code

#include <iostream>
#include <system_error>
 
int main()
{
    try
    {
        throw std::system_error(EDOM, std::generic_category(), "hello world");
    }
    catch (const std::system_error& ex)
    {
        std::cout << ex.code() << '\n';
        std::cout << ex.code().message() << '\n';
        std::cout << ex.what() << '\n';
    }
}

Possible output:

generic:33
Numerical argument out of domain
hello world: Numerical argument out of domain