C++求找错（输入三个数，按由大到小顺序打印出来）感谢（初学）

#include <iostream>
using namespace std;

int main( void )
{
    float a, b, c;
    cin >> a >> b >> c;

    if( a > b )
    {
        float t = a;
        a = b;
        b = t;
    }

    if( a > c )
    {
        float t = a;
        a = c;
        c = t;
    }

    if( b > c )
    {
        float t = b;
        b = c;
        c = t;
    }

    cout << c << " " << b << " " << a << endl;
}

#include <iostream>
#include <iterator>
#include <algorithm>
using namespace std;

int main( void )
{
    double buf[3];
    copy_n( istream_iterator<double>(cin), 3, buf );

    sort( begin(buf), end(buf), greater<double>() );

    copy( begin(buf), end(buf), ostream_iterator<double>(cout," ") );
}