24 Strings library [strings]

24.3 String classes [string.classes]

24.3.2 Class template basic_­string [basic.string]

24.3.2.6 basic_­string modifiers [string.modifiers]

24.3.2.6.7 basic_­string​::​copy [string.copy]

size_type copy(charT* s, size_type n, size_type pos = 0) const;
Let rlen be the smaller of n and size() - pos.
Throws: out_­of_­range if pos > size().
Requires: [s, s + rlen) is a valid range.
Effects: Equivalent to traits​::​copy(s, data() + pos, rlen).
[Note
:
This does not terminate s with a null object.
end note
]
Returns: rlen.