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Write a C program that does not terminate when Ctrl+C is pressed

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  • Difficulty Level : Hard
  • Last Updated : 21 Jun, 2022
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Write a C program that doesn’t terminate when Ctrl+C is pressed. It prints a message “Cannot be terminated using Ctrl+c” and continues execution. We can use signal handling in C for this. When Ctrl+C is pressed, SIGINT signal is generated, we can catch this signal and run our defined signal handler.  C standard defines following 6 signals in signal.h header file. SIGABRT – abnormal termination. SIGFPE – floating point exception. SIGILL – invalid instruction. SIGINT – interactive attention request sent to the program. SIGSEGV – invalid memory access. SIGTERM – termination request sent to the program. Additional signals are specified Unix and Unix-like operating systems (such as Linux) defines more than 15 additional signals. See http://en.wikipedia.org/wiki/Unix_signal#POSIX_signals The standard C library function signal() can be used to set up a handler for any of the above signals. 

C




/* A C program that does not terminate when Ctrl+C is pressed */
#include <stdio.h>
#include <signal.h>
 
/* Signal Handler for SIGINT */
void sigintHandler(int sig_num)
{
    /* Reset handler to catch SIGINT next time.
    signal(SIGINT, sigintHandler);
    printf("\n Cannot be terminated using Ctrl+C \n");
    fflush(stdout);
}
 
int main ()
{
    /* Set the SIGINT (Ctrl-C) signal handler to sigintHandler
    signal(SIGINT, sigintHandler);
 
    /* Infinite loop */
    while(1)
    {        
    }
    return 0;
}

Output: When Ctrl+C was pressed two times

 
 Cannot be terminated using Ctrl+C
 
 Cannot be terminated using Ctrl+C

Time Complexity: O(1)

Auxiliary Space: O(1)

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