SIG_DFL, SIG_IGN

From cppreference.com
< cpp‎ | utility‎ | program
Defined in header <csignal>
#define SIG_DFL /*implementation defined*/
#define SIG_IGN /*implementation defined*/

The SIG_DFL and SIG_IGN macros expand into integral expressions that are not equal to an address of any function. The macros define signal handling strategies for std::signal() function.

Constant Explanation
SIG_DFL default signal handling
SIG_IGN signal is ignored

[edit] See also

C documentation for SIG_DFL, SIG_IGN