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std::system_error

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.

cpp/error/exception cpp/error/runtime errorstd-system error-inheritance.svg

Inheritance diagram.

Member functions

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

Inherited from std::exception

Member functions

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

Example

#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

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