int sputn( const char* pch, int nCount );
pch
A pointer to a buffer that contains data to be copied to the streambuf object.
nCount
The number of characters in the buffer.
Copies nCount characters from pch to the streambuf buffer following the put pointer. The function repositions the put pointer to follow the stored characters.
The number of characters stored. This number is usually nCount but could be less if an error occurs.