default constructor (1)

Error code with a value of 0 of the system_category (generally indicating no error).

initialization constructor (2)

Error code with a value of val of the category specified by cat.

construct from error code enum type (3)

Calls make_error_code to construct an error code.
This constructor only participates in overload resolution if is_error_code_enum<ErrorCodeEnum>::value is true.

Parameters

val

A numerical value identifying an error code.

cat

A reference to an error_category object.

e

Error code enum value of an enum type for which is_error_code_enum has a value member with a value of true.

Example

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// error_code constructors
#include <iostream>       // std::cout
#include <cmath>          // std::sqrt
#include <cerrno>         // errno
#include <system_error>   // std::error_code, std::generic_category
                          // std::error_condition
int main()
{
  errno=0;
  std::sqrt(-1.0);        // errno set to EDOM
  std::error_code ec (errno,std::generic_category());

  std::error_condition ok;
  if (ec != ok) std::cout << "Error: " << ec.message() << '\n';

  return 0;
}

See also

error_code::operator=

Assign error code (public member function)

error_code::assign

Assign error code (public member function)

error_code::clear

Clear error code (public member function)