C++ output ont coming

Question

Output should be come:
2
4
a := 2 b:= 4

a:= 4 b: =2
https://code.sololearn.com/c1CO62vGzWmf/?ref=app

Answer 1

#include<iostream>
#include<cstdio>
using namespace std; // make the std built-in symbols active, instead of std::cin, std::cout, etc.

void swap(float &x ,float &y)
{
float t=x;
x=y;
y=t;
}
int main() // cpp standard， instead of "void main" in c standard
{
void swap(float &,float &);
float a,b;
cin>>a>>b;
cout<<"a:="<<a<<"b:="<<b<<endl;
swap(a,b);
cout<<"a:="<<a<<"b:="<<b<<endl;
return 0; // must return an int
}

Answer 2

https://code.sololearn.com/c1CO62vGzWmf/?ref=app