C++, Pass by Pointers

Question

I was actually thinking that this program should throw a Compilation Error(coz, I am passing values to swap method and not &a, &b) but I was shocked to see that it got executed Successfully. So, am posting this to know how/why it got executed without any error.

#include <iostream> 
using namespace std; 

void swap(int* x, int* y) 
{ 
    int z = *x; 
    *x = *y; 
    *y = z; 
} 

int main() 
{ 
    int a = 45, b = 35; 
    cout << "Before Swap\n"; 
    cout << "a = " << a << " b = " << b << "\n";  
    swap(a, b); 

    cout << "After Swap with pass by pointer\n"; 
    cout << "a = " << a << " b = " << b << "\n"; 
}

`swap(&a, &b);` note that you are using `using namespace std;` and there is `std::swap`. — Marek R, Jan 12 '21 at 17:03
Thank you for the comments. I am just trying to know if I am getting it right, so what's happening is, when I call swap(a,b) and since I have not defined a swap function that receives values. Therefore it is searching for the function in the STD and because it found one there, it is getting executed, correct? — Jayanth G, Jan 12 '21 at 17:24

score 4 · Answer 1 · answered Jan 12 '21 at 17:05

4

As is said so often on this site, using namespace std; is a bad idea.

You called std::swap<int>

answered Jan 12 '21 at 17:05

MSalters

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Hey, thank you for your time. – Jayanth G Jan 12 '21 at 17:12
I am just trying to know if I am getting it right, so what's happening is, when I call swap(a,b) and since I have not defined a swap function that receives values. Therefore it is searching for the function in the STD and because it found one there, it is getting executed, correct? – Jayanth G Jan 12 '21 at 17:15
1

It doesn't search in `std`. You took all of the contents of `std` and put everything in the global namespace, the same namespace where you defined your own `std::swap`. Searches will look at surrounding namespaces, but not inside nested namespaces. – MSalters Jan 12 '21 at 17:25
I see, thanks a lot for clearing my doubts. – Jayanth G Jan 13 '21 at 12:17

C++, Pass by Pointers

1 Answers1