== `exit_code.hpp`
[#exit_code]

The exit code header provides portable handles for exit codes.

[source,cpp]
----
// The native exit-code type, usually an integral value
/* The OS may have a value different from `int` to represent
 * the exit codes of subprocesses. It might also
 * contain additional information.
 */
typedef implementation_defined native_exit_code_type;


// Check if the native exit code indicates the process is still running
bool process_is_running(native_exit_code_type code);

// Obtain the portable part of the exit code, i.e. what the subprocess has returned from main.
int evaluate_exit_code(native_exit_code_type code);

// Helper to subsume an exit-code into an error_code if there's no actual error isn't set.
error_code check_exit_code(
    error_code &ec, native_exit_code_type native_code,
    const error_category & category = error::get_exit_code_category());
----


The `check_exit_code` can be used like this:

[source,cpp]
----

process proc{co_await this_coro::executor, "exit", {"1"}};

co_await proc.async_wait(
    asio::deferred(
     [&proc](error_code ec, int)
     {
       return asio::deferred.values(
                 check_exit_code(ec, proc.native_exit_code())
             );
----