double and stringstream formatting

Question

double val = 0.1;
std::stringstream ss;
ss << val;
std::string strVal= ss.str();

In the Visual Studio debugger, val has the value 0.

Answer 1

You can change the floating-point precision of a stringstream as follows:

double num = 2.25149;
std::stringstream ss(stringstream::in | stringstream::out);
ss << std::setprecision(5) << num << endl;
ss << std::setprecision(4) << num << endl;

Output:

2.2515
2.251

Note how the numbers are also rounded when appropriate.