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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