c++ 的string的格式化方法

1. 

        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 

#include 

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));