C++ In a Nutshell

<sstream>

The <sstream> header declares classes, templates, and other types for reading from and writing to strings in the same manner as reading from and writing to files.

See Chapter 9 for a general discussion of I/O, Chapter 1 for more information about character sets, and the <iostream> section in this chapter for information about the base-class templates required by the stringstream class templates. Refer to Chapter 8 for information about traits in general and to the <string> section in this chapter for detailed information about the char_traits template. Refer to the <streambuf> section in this chapter for information about the basic_streambuf template. See also <strstream> for classes that are similar to the string streams, except they work with arrays of narrow characters.

To read from a string, use istringstream; for writing, use ostringstream; for reading and writing, use stringstream. For wide character I/O, use wistringstream, wostringstream, or wstringstream. Example 13-35 shows tostring, a simple use of ostringstream to convert a value to a string. (Think of tostring as the inverse of strtol and friends.)

Example 13-35. Converting a value to a string

template<typename T>
std::string tostring(const T& x)
{
  std::ostringstream out;
  out << x;
  return out.str(  );
}

Example 13-36 shows a use of istringstream to interpret HTML colors. In HTML, a color can be a name, such as white, or a hexadecimal digit string that begins with #. The digit string is interpreted as a triplet ...