Signal Handling in C++
Signals are the interrupts that force an OS to stop its ongoing task and attend the task for which the interrupt has been sent. These interrupts can pause service in any program of an OS. Similarly, C++ also offers various signals which it can catch and process in a program. Here is a list of various signals and their operations that C++ provides the user to work with. Operations SIGINT SIGTERM SIGBUS SIGILL SIGALRM SIGABRT SIGSTOP SIGSEGV SIGFPE SIGUSR1 SIGSUR2
Signals produces a receipt for an active signal Sends a termination request to the program Bus error which indicates access to an invalid address Detects an illegal command This is used by the alarm() function and indicates the expiration of the timer. Termination of a program, abnormally The signal cannot be blocked, handled, and ignored and can stop a process Invalid access to storage Overflow operations or mathematically incorrect operations like divide by zero User-Defined Signals
This signal() function is provided by the signal library and is used to trap unexpected interrupts or events.
signal(registered signal, signal handler)
The first argument is an integer, representing the signal number and second is the pointer to a signal handling function. We must keep in mind that the signal that we would like to catch must be registered using a signal function and it must be associated with a signal handling function. The signal handling function should be of the void type.
Output: Being in an infinite loop this code will show the following output until an interrupt is faced:
Hello GeeksforGeeks... Hello GeeksforGeeks... Hello GeeksforGeeks... Hello GeeksforGeeks...
Now if we press Ctrl+C to send an interrupt, the program will exit by printing:
Hello GeeksforGeeks... Hello GeeksforGeeks... Hello GeeksforGeeks... Hello GeeksforGeeks... The interrupt signal is (22).
The raise() function is used to generate signals.
raise( signal )
It takes an argument as any of the functions mentioned in the list.
Hello GeeksforGeeks... Hello GeeksforGeeks... Hello GeeksforGeeks... Hello GeeksforGeeks... Hello GeeksforGeeks... Interrupt signal is (11).
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