ios_base::修复了截断尾随零(&T)

当打印某些十进制数时,可能会发生舍入(我目前的平台是ibmiseries)。如果我设置ios_base::fixed,效果会更好,但会打印讨厌的尾随(和无关紧要的)零。有没有更好的办法?对于我使用的平台,输出如下:

myval=100000
myval=99999.990000
myval as string =99999.990000

#include <iostream>
#include <string>
#include <sstream>
#include <iomanip>
#include <unistd.h>
#include <algorithm>

using namespace std;

// returns t
template<typename T> string toString(const T& val)
{
    stringstream os;

    os.setf(std::ios_base::fixed);
    os << val;
    return os.str();
}

class MyApp {
private :
public :
    MyApp();
    virtual ~MyApp();

    void run();

    operator bool() const { return true; }
};


MyApp::MyApp()
{
}

MyApp::~MyApp()
{
}

void MyApp::run()
{
    double myval = 99999.99;
    string myval_as_string = toString<double>(myval);

    cout << "myval=" << myval << endl;

    cout.setf(std::ios_base::fixed);

    cout << "myval=" << myval << endl;
    cout << "myval as string =" << myval_as_string << endl;
}

int main(int argc, char* argv[])
{
    MyApp myApp;

    myApp.run();
}