I am not sure about the “most elegant way” but here’s one way.
#include <iostream>
#include <iomanip>
#include <sstream>
using namespace std ;
string fix( float x, int p )
{
ostringstream strout ;
strout << fixed << setprecision(p) << x ;
string str = strout.str() ;
size_t end = str.find_last_not_of( '0' ) + 1 ;
return str.erase( end ) ;
}
int main()
{
float a = 0.000001f ;
float b = 0.1f ;
cout << "a: " << fix( a, 6 ) << endl; // 0.000001 ok.
cout << "b: " << fix( b, 6 ) << endl; // 0.1 ok.
return 0;
}
You could perhaps create your own I/O manipulator if you need to to a lot of this kind of output. That is arguably more elegant, but the implementation could be similar.