copy()
and swap()
The copy()
method copies a string
object, or part thereof, to a designated character array:
size_type copy(charT* s, size_type n, size_type pos = 0) const;
In this case, s
points to the destination array, n
indicates the number of characters to copy, and pos
indicates the position in the string
object from which copying begins. Copying proceeds for n
characters or until the last character in the string
object, whichever comes first. The function returns the number of characters copied. The method does not append a null character, and it is up to the programmer to see that the array is large enough to hold the copy.
The copy()
method does not append a null character, nor does it check whether the destination array is large enough.
The swap()
method swaps the contents of two string
objects by using a constant time algorithm:
void swap(basic_string& str);
The string
class overloads the <<
operator to display string
objects. It returns a reference to the istream
object so that output can be concatenated:
string claim("The string class has many features.");
cout << claim << endl;
The string
class overloads the >>
operator so that you can read input into a string:
string who;
cin >> who;
Input terminates on the end-of-file, on reading the maximum number of characters allowed in a string, or on reaching a white-space character. (The definition of white space depends on the character set and on the type that charT
represents.)
There are two getline()
functions. The first has this prototype:
template<class charT, class traits, class Allocator>
basic_istream<charT,traits>& getline(basic_istream<charT,traits>& is,
basic_string<charT,traits,Allocator>& str, charT delim);
It reads characters from the input stream is
into the string str
until it encounters the delim
delimiter character, reaches the maximum size of the string, or encounters the end-of-file. The delim
character is read (that is, removed from the input stream) but not stored. The second version lacks the third argument and uses the newline character (or its generalization) instead of delim
:
string str1, str2;
getline(cin, str1); // read to end-of-line
getline(cin, str2, '.'), // read to period
3.149.27.72