CODEWITHSUNDEEP
c++qt
Jérôme
Jérôme

Reputation: 27047

long double to string

I'm developping in C++, using the Qt framework.

I need to convert a long double value into a string (ideally a QString, but could be something else).

So far, I always used QString::number() for numerical->string conversion, but there is no overloading for the long doubletype.

Thanks

Upvotes: 2

Views: 9330

Answers (4)

Piotr Borys
Piotr Borys

Reputation: 51

The answer marked is not complete, it will save it with only 6 decimal digits. It should be like this:

#include <sstream>
#include <iomanip>
#include <limits>

QString longDoubleToString(long double value)
    {
    std::stringstream stream;
    stream << std::fixed << std::setprecision(std::numeric_limits<long double>::digits10 + 1) << value;
    return QString::fromStdString(stream.str());
    }

Upvotes: 0

wheaties
wheaties

Reputation: 35990

Simple:

string convert(long double myLongDouble) {
    stringstream blah;
    blah << myLongDouble;

    return blah.str();
}

With Templates:

template<class T> string convert(T _input) {
    stringstream blah;
    blah << _input;

    return blah.str();
}

Upvotes: 5

Bill
Bill

Reputation: 14695

QString has a static function to construct a QString from a std::string, so wheaties' answer could be rewritten as:

#include <sstream>
#include <QString>
...
QString qStringFromLongDouble(const long double myLongDouble)
{
  std::stringstream ss;
  ss << myLongDouble;

  return QString::fromStdString(ss.str());
}

Upvotes: 5

Fred Larson
Fred Larson

Reputation: 62123

Boost has lexical_cast for this purpose. It pretty much wraps the solution wheaties gave into a class template.

Upvotes: 0

Related Questions