return statement vs exit() in main() - GeeksforGeeks
return statement vs exit() in main()
- Difficulty Level : Medium
- Last Updated : 28 May, 2017
In C++, what is the difference between exit(0) and return 0 ?
When exit(0) is used to exit from program, destructors for locally scoped non-static objects are not called. But destructors are called if return 0 is used.
Program 1 – – uses exit(0) to exit
#include<iostream>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
class Test {
public:
Test() {
printf("Inside Test's Constructor\n");
}
~Test(){
printf("Inside Test's Destructor");
getchar();
}
};
int main() {
Test t1;
// using exit(0) to exit from main
exit(0);
}
Output:
Inside Test’s Constructor
Program 2 – uses return 0 to exit
#include<iostream>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
class Test {
public:
Test() {
printf("Inside Test's Constructor\n");
}
~Test(){
printf("Inside Test's Destructor");
}
};
int main() {
Test t1;
// using return 0 to exit from main
return 0;
}
Output:
Inside Test’s Constructor
Inside Test’s Destructor
Calling destructors is sometimes important, for example, if destructor has code to release resources like closing files.
Note that static objects will be cleaned up even if we call exit(). For example, see following program.
#include<iostream>
#include<stdio.h>
#include<stdlib.h>
using namespace std;
class Test {
public:
Test() {
printf("Inside Test's Constructor\n");
}
~Test(){
printf("Inside Test's Destructor");
getchar();
}
};
int main() {
static Test t1; // Note that t1 is static
exit(0);
}
Output:
Inside Test’s Constructor
Inside Test’s Destructor