< cpp‎ | io‎ | basic stringbuf
Revision as of 22:00, 31 May 2013 by P12bot (Talk | contribs)

std::basic_string<CharT, Traits, Allocator> str() const;
void str( const std::basic_string<CharT, Traits, Allocator>& s);

Gets and sets the underlying string.

1) Creates and returns a std::basic_string object containing a copy of this std::basic_stringbuf's underlying character sequence. For input-only streams, the returned string contains the characters from the range [eback(), egptr()). For input/output or output-only streams, contains the characters from pbase() to the last character in the sequence regardless of egptr() and epptr().
2) Deletes the entire underlying character sequence of this std::basic_stringbuf and then configures a new underlying character sequence containing a copy of the contents of s. The pointers of std::basic_streambuf are initialized as follows:
For input streams (mode & ios_base::in == true), eback() points at the first character, gptr() == eback(), and egptr() == eback() + s.size(): the subsequent input will read the first character copied from s.
For output streams (mode & ios_base::out == true), pbase() points at the first character and epptr() >= pbase() + s.size() (epptr is allowed to point farther so that the following sputc() wouldn't immediately call overflow())
For append streams (mode & ios_base::ate == true), pptr() == pbase() + s.size(), so that subsequent output will be appended to the last character copied from s (since C++11)
For no-appending output streams, pptr() == pbase(), so that subsequent output will overwrite the characters copied from s.



s - a string object holding the replacement character sequence

Return value

1) A string object holding a copy of this buffer's underlying character sequence.
2) (none)


This function is typically accessed through std::basic_stringstream::str().


#include <sstream>
#include <iostream>
int main()
    int n;
    std::istringstream in;  // could also use in("1 2")
    in.rdbuf()->str("1 2"); // set the get area
    in >> n;
    std::cout << "after reading the first int from \"1 2\", the int is " 
              << n << ", str() = \"" << in.rdbuf()->str() << "\"\n"; // or in.str()
    std::ostringstream out("1 2");
    out << 3;
    std::cout << "after writing the int '3' to output stream \"1 2\""
              << ", str() = \"" << out.str() << "\"\n";
    std::ostringstream ate("1 2", std::ios_base::ate); // C++11
    ate << 3;
    std::cout << "after writing the int '3' to append stream \"1 2\""
              << ", str() = \"" << ate.str() << "\"\n";


after reading the first int from "1 2", the int is 1, str() = "1 2"
after writing the int '3' to output stream "1 2", str() = "3 2"
after writing the int '3' to append stream "1 2", str() = "1 23"

See also

gets or sets the contents of underlying string device object
(public member function of std::basic_stringstream) [edit]