cpp/io/basic istream/readsome

Extracts up to immediately available characters from the input stream. The extracted characters are stored into the character array pointed to by.

Behaves as. After constructing and checking the sentry object,


 * If, calls and extracts no characters.


 * If, extracts no characters.


 * If, extracts characters and stores them into successive locations of the character array whose first element is pointed to by.

Return value
The number of characters actually extracted.