C++: Formatting float to string with arbitrary decimal digits

gistfile1.cpp

std::stringstream ss;

// set a flag to formatting with decimal digits
ss.setf(std::ios_base::fixed, std::ios_base::floatfield);

float f = 1.555555;

// set a nuber of digits
ss.precision(2);
ss << "Float: " <<f;

printf("%s\n", ss.str().c_str()); // "Float: 1.55"
    
// reset a flag    
ss.setf(std::ios_base::fmtflags(0), std::ios_base::floatfield);