# std::basic_ios<CharT,Traits>::rdbuf

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< cpp‎ | io‎ | basic ios

std::basic_streambuf <CharT, Traits>* rdbuf() const; | (1) |
std::basic_streambuf <CharT, Traits>* rdbuf( std::basic_streambuf <CharT, Traits>* sb ); | (2) |

Manages the associated stream buffer.

1) Returns the associated stream buffer. If there is no associated stream buffer, returns a null pointer.
2) Sets the associated stream buffer to `sb`. The error state is cleared by calling clear(). Returns the associated stream buffer before the operation. If there is no associated stream buffer, returns a null pointer.

### Parameters

sb | - | stream buffer to associate to

### Return value

The associated stream buffer, or a null pointer if there was no associated stream buffer.

### Exceptions

(none)

### Example

Run this code

    #include <iostream>
    #include <sstream>

    int main()
    {
        std::ostringstream local;
        auto cout_buff = std::cout.rdbuf(); // save pointer to std::cout buffer

        std::cout.rdbuf(local.rdbuf()); // substitute internal std::cout buffer with
            // buffer of 'local' object

        // now std::cout work with 'local' buffer
        // you don't see this message
        std::cout << "some message";

        // go back to old buffer
        std::cout.rdbuf(cout_buff);

        // you will see this message
        std::cout << "back to default buffer\n";

        // print 'local' content
        std::cout << "local content: " << local.str() << "\n";
    }

Output:

    back to default buffer
    local content: some message

### See also

set_rdbuf | replaces the `rdbuf` without clearing its error state (protected member function)

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