NAME¶

std::system_error::system_error - std::system_error::system_error

Synopsis¶

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, (4) (since C++11)
const std::string& what_arg );
system_error( int ev, const std::error_category& ecat, (4) (since C++11)
const char* what_arg );
system_error( const system_error& other ) noexcept; (5) (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 (assuming that it doesn't contain an embedded null character
).
5) Copy constructor. Initializes the contents with those of other. If *this and
other both have dynamic type std::system_error then std::strcmp(what(),
other.what()) == 0.

Parameters¶

ec - error code
ev - underlying error code in the enumeration associated with ecat
ecat - the category of error
what_arg - explanatory string
other - another system_error to copy

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