EXIT_SUCCESS, EXIT_FAILURE
Min standard notice:
Header: <cstdlib>
The EXIT_SUCCESS and EXIT_FAILURE macros expand into integral constant expressions that can be used as arguments to the std::exit function (and, therefore, as the values to return from the main function), and indicate program execution status.
# Declarations
#define EXIT_SUCCESS /*implementation defined*/
#define EXIT_FAILURE /*implementation defined*/
# Notes
Both EXIT_SUCCESS and the value zero indicate successful program execution status (see std::exit), although it is not required that EXIT_SUCCESS equals zero.
Although EXIT_SUCCESS and EXIT_FAILURE are required to be freestanding since C++23, they are not required to be available in a freestanding C implementation.
# Example
#include <cstdlib>
#include <iostream>
int main(int argc, char* argv[])
{
if (argc <= 1)
{
std::cout << "At least one command-line argument required\n";
return EXIT_FAILURE;
}
std::cout << argv[1] << '\n';
return EXIT_SUCCESS;
}