Use of exit() function

Question

I want to know how and when can I use the exit() function like the program in my book:

#include

void main()
{
    int goals;
            


        

Answer 1

In addition to return an exit code to parent process -

In UNIX, an important aspect that I think has been left out is, that exit() at first calls (in reverse order) all those functions, which were registered by atexit() call.

Please refer to SUSv4 for details.

Answer 2

on unix like operating systems exit belongs to group of system calls. system calls are special calls which enable user code (your code) to call kernel code. so exit call makes some OS specific clean-up actions before returning control to OS, it terminates the program.

#include <stdlib.h>

// example 1
int main(int argc, char *argv){
  exit(EXIT_SUCCESS);
}

// example 2
int main(int argc, char *argv){
  return 0;
}

Some compilers will give you the same opcode from both of these examples but some won't. For example opcode from first function will not include any kind of stack positioning opcode which will be included in the second example like for any other function. You could compile both examples and disassemble them and you will see the difference.

You can use exit from any part of your code and be sure that process terminates. Don't forget to include integer parameter.

Answer 3

Write header file #include<process.h> and replace exit(); with exit(0);. This will definitely work in Turbo C; for other compilers I don't know.

Answer 4

Bad programming practice. Using a goto function is a complete no no in C programming.
Also include header file stdlib.h by writing #include <iostream.h>for using exit() function. Also remember that exit() function takes an integer argument . Use exit(0) if the program completed successfully and exit(-1) or exit function with any non zero value as the argument if the program has error.

Answer 5

Use process.h instead of stdlib and iostream... It will work 100%.

Answer 6

The following example shows the usage of the exit() function.

#include <stdio.h>
#include <stdlib.h>

int main(void) {
    printf("Start of the program....\n");
    printf("Exiting the program....\n");
    exit(0);
    printf("End of the program....\n");
    return 0;
}

Output

Start of the program....
Exiting the program....