Converting Double to String in C++

问题:

I am having some issues trying to convert a double to C++ string. Here is my code

std::string doubleToString(double val)
{
    std::ostringstream out;
    out << val;
    return out.str();
}

The problem I have is if a double is being passed in as '10000000'. Then the string value being returned is 1e+007

How can i get the string value as "10000000"

回答1:

#include <iomanip>
using namespace std;
// ...
out << fixed << val;
// ...

You might also consider using setprecision to set the number of decimal digits:

out << fixed << setprecision(2) << val;

回答2:

#include <iomanip>

std::string doubleToString(double val)
{
   std::ostringstream out;
   out << std::fixed << val;
   return out.str();
}

回答3:

You can also set the minimum width and fill char with STL IO manipulators, like:

out.width( 9 );
out.fill( ' ' );