### Program Signal Handling

Use the signal function to specify how to handle signals. For each signal, you can specify one of the types of handlers listed below. The signal constants are defined in the signal.h header file.

1. SIG_DFL
   Specifies the default action. This is the initial setting for all signals. For most signals, the default action is to terminate the process with an error message. If you build your program with the /Tx+ compiler option , the default action can be accompanied by a dump of the machine state. The dump is sent to file handle 2, which is usually associated with stderr. Call the _set_crt_msg_handle function to change the destination of the machine-state dump and other messages.
2. SIG_IGN
   Ignores the condition and tries to continue running the program. If you specify SIG_IGN for a signal that cannot be ignored, such as division by zero, the VisualAge for C++ library treats the signal as if SIG_DFL was specified.
3. Your own signal handler function
   Registers the function you specify. This can be a function you have written. When the signal is reported and your function is called, signal handling is reset to SIG_DFL to prevent recursion should the same signal be reported from your function.

To reset default handling for a signal, call the signal in a statement similar to the following. Specify the signal name in the first argument of signal.

>     signal(sig, SIG_DFL);

Signals and Exceptions
Signal and Exception Handling

Write or Register a Signal Handler

Default Signal Handlers