标准的c++中int，float，double等怎么转换成string类,并实现文件写入

c++的标准作法是通过stringstream。

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
using namespace std;
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    ofstream out;
    out.open("Hello.txt", ios::in|ios::out|ios::binary|ios::app);
    stringstream ss;
    string str;
    int i = 1;
    float f = 10.1;
    double d = 100.11;

    ss << i << "," << f << "," << d << endl;
    ss >> str;
    out << str;
    out.close();
    return a.exec();
}

将数字1,10.1,100.11，输入到文件Hello.txt中