What will be the output of the following C++ code?
#include <iostream>
using namespace std;
void swap(int &a, int &b);
int main()
{
int a = 5, b = 10;
swap(a, b);
cout << "In main " << a << b;
return 0;
}
void swap(int &a, int &b)
{
int temp;
temp = a;
a = b;
b = temp;
cout << "In swap " << a << b;
}
a) In swap 105 In main 105
b) In swap 105 In main 510
c) In swap 510 In main 105
d) In swap 510 In main 510

Answer: a
Explanation: As the function is called by reference i.e. all the changes are done directly into the memories of a and b. Therefore changes made to a and b in swap function is reflected back to main function. Hence the values of a and b in swap as well as in main function is changed.
Output:
In swap 105 In main 105