what is the purpose of atexit function?

I know when the address of the function is passed to atexit function,

the function is excuted.

#include <stdlib.h>
int atexit(void (*func) void));

However, what is the purpose of using atexit function?

Does verbal meaning itself 'exit' r开发者_高级运维elate to atexit function?

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atexit would be used for some code that you want to execute when the application terminates, regardless of where it was exited from. One example would be an application-wide logger. You would call atexit(flush_log), so when the application exits, the log will be flushed, without the developer having to remember to flush it.

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Yes, atexit is related to exit.

exit can call functions which are automatically called before a program exits. These functions are called exit handlers and are registered by calling atexit function.

#include<stdio.h>                 

main(void) {                        
atexit(func);
}

func(void) 
{
    ...
}

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#include<stdlib.h>
int atexit(void (*func)(void));

The above declaration says that we pass the address of a function as the argument to atexit. When this function is called, it is not passed any arguments and is not expected to return a value. The exit function called these functions in reverse order of their registration. Each function is called as many times as they registered.