c++ 的string的格式化方法...

        string strResult,str;
        double a=35.000,b=14.967;
        std::ostringstream   ostr; 
ostr   <<   "a+b="   <<   a   <<   "+"   <<   b   <<   "="   <<   a+b;
std::string str = ostr.str();
strResult += str;

2.

#include <sstream>
#include <iostream>
using namespace std;
ostringstream ostr;
ostr << "d = " << 123 << "f = " << 12.345 << "test format" << std:endl;
string str = ostr.str();
cout << ostr.str().c_str();

以上两种方法中，double数值也默认显示为整数。

3.

char buf[1024];
sprintf(buf,"a+b=%f+%f=%f",a,b,a+b);
memset(buf,0,sizeof(buf));