In C, exit() terminates the calling process without executing the rest code which is after the exit() function.
Example:-
// C program to illustrate exit() function. #include <stdio.h> #include <stdlib.h> int main( void ) { printf ( "START" ); exit (0); // The program is terminated here // This line is not printed printf ( "End of program" ); } |
Output:
START
Now the question is that if we have exit() function then why C11 standard introduced _Exit()? Actually exit() function performs some cleaning before termination of the program like connection termination, buffer flushes etc. The _Exit() function in C/C++ gives normal termination of a program without performing any cleanup tasks. For example it does not execute functions registered with atexit.
Syntax:
// Here the exit_code represent the exit status // of the program which can be 0 or non-zero. // The _Exit() function returns nothing. void _Exit(int exit_code);
// C++ program to demonstrate use of _Exit() #include <stdio.h> #include <stdlib.h> int main( void ) { int exit_code = 10; printf ( "Termination using _Exit" ); _Exit(exit_code); } |
Output:
Showing difference through programs:
// A C++ program to show difference // between exit() and _Exit() #include<bits/stdc++.h> using namespace std; void fun( void ) { cout << "Exiting" ; } int main() { atexit (fun); exit (10); } |
Output
Exiting
If we replace exit with _Exit(), then nothing is printed.
// A C++ program to show difference // between exit() and _Exit() #include<bits/stdc++.h> using namespace std; void fun( void ) { cout << "Exiting" ; } int main() { atexit (fun); _Exit(10); } |
Output
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