io:sstream:constructors

C++ Reference

String Stream Constructors

Syntax:

    #include <sstream>
    stringstream()
    stringstream( openmode mode )
    stringstream( string s, openmode mode )
    ostringstream()
    ostringstream( openmode mode )
    ostringstream( string s, openmode mode )
    istringstream()
    istringstream( openmode mode )
    istringstream( string s, openmode mode )

The stringstream, ostringstream, and istringstream objects are used for input and output to a string. They behave in a manner similar to fstream, ofstream and ifstream objects. The optional mode parameter defines how the file is to be opened, according to the io_stream_mode_flags. An ostringstream object can be used to write to a string. This is similar to the C sprintf() function. For example:

    ostringstream s1;
    int i = 22;
    s1 << "Hello " << i << endl;
    string s2 = s1.str();
    cout << s2;

An istringstream object can be used to read from a string. This is similar to the C sscanf() function. For example:

    istringstream stream1;
    string string1 = "25";
    stream1.str(string1);
    int i;
    stream1 >> i;
    cout << i << endl;  // displays 25

You can also specify the input string in the istringstream constructor as in this example:

    string string1 = "25";
    istringstream stream1(string1);
    int i;
    stream1 >> i;
    cout << i << endl;  // displays 25

A stringstream object can be used for both input and output to a string like an fstream object.