INTERVIEW QUESTIONS C FUNCTIONS IN C DETAILS

Question: Is it possible to execute code even after the program exits the main() function?

Answer: The standard C library provides a function named atexit() that can be used to perform “cleanup” operations when your program terminates. You can set up a set of functions you want to perform automatically when your program exits by passing function pointers to the atexit() function.

The standard C library provides a function named atexit() that can be used to perform “cleanup” operations when your program terminates. You can set up a set of functions you want to perform automatically when your program exits by passing function pointers to the atexit() function. Source: CoolInterview.com

it is not at all possible to execute the code after exit the main.

Source: CoolInterview.com

Yes, It is possible execute code even after the program exits the main() function.
Explanation :-
We can crate Child Process(Thread)and make the child process to sleep and by that time, we can make the Main thread to finish its execution and exit. ( In C main() act as the Main Thread ).After the main thread exits, the child thread can run after coming from sleep state. Source: CoolInterview.com

the atexit() function is called before exiting the main() function and it is not at all possible to carry on execution after exiting the main() function. Source: CoolInterview.com

Using atexit() we can execute code even after exit from main program.

I think the following program will help in understanding the concept.

Here, I am initializing the function that has to be executed after exit of the main program, printing some output and calling the return, which exits the function. Later i am printing some more lines of code (which i am sure that wont be called as the function is exited). Once the function exits, it will call the funcion which is initialized using atexit().

#include<stdio.h>

void myFunction_Onexit()
{
printf("
Welcome to user exit function.

Here u can do anything
");
system("pause");
}
int main()
{

printf("
In main function before return
");
atexit(myFunction_Onexit);
system("pause");
return 0;
printf("
In main function after return
");
system("pause");
return 0;

}
Source: CoolInterview.com

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