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`<string>`

string · char_allocator · char_traits · getline · operator+ · operator!= · operator== · operator< · operator<< · operator<= · operator> · operator>= · operator>> · swap

Include the standard header <string> to define the class string and various supporting classes and functions.

        // DECLARATIONS
class char_allocator;
class char_traits;
class string;

        // FUNCTIONS
string operator+(
    const string& left,
    const string& right);
string operator+(
        const string& left,
        const char *right);
string operator+(
    const string& left,
    char right);
string operator+(
    const char *left,
    const string& right);
string operator+(
    char left,
    const string& right);
bool operator==(
    const string& left,
    const string& right);
bool operator==(
    const string& left,
    const char *right);
bool operator==(
    const char *left,
    const string& right);
bool operator!=(
    const string& left,
    const string& right);
bool operator!=(
    const string& left,
    const char *right);
bool operator!=(
    const char *left,
    const string& right);
bool operator<(
    const string& left,
    const string& right);
bool operator<(
    const string& left,
    const char *right);
bool operator<(
    const char *left,
    const string& right);
bool operator>(
    const string& left,
    const string& right);
bool operator>(
    const string& left,
    const char *right);
bool operator>(
    const char *left,
    const string& right);
bool operator<=(
    const string& left,
    const string& right);
bool operator<=(
    const string& left,
    const char *right);
bool operator<=(
    const char *left,
    const string& right);
bool operator>=(
    const string& left,
    const string& right);
bool operator>=(
    const string& left,
    const char *right);
bool operator>=(
    const char *left,
    const string& right);
void swap(
    string& left,
    string& right);
ostream& operator<<(
    ostream& ostr,
    const string& str);
istream& operator>>(
    istream& istr,
    string& str);
istream& getline(
    istream& istr,
    string& str);
istream& getline(
    istream& istr,
    string& str,
    char delim);
        // END OF DECLARATIONS

`string`

string · allocator_type · append · assign · at · begin · c_str · capacity · clear · compare · const_iterator · const_pointer · const_reference · const_reverse_iterator · copy · data · difference_type · empty · end · erase · find · find_first_not_of · find_first_of · find_last_not_of · find_last_of · get_allocator · insert · iterator · length · max_size · npos · operator+= · operator= · operator[] · pointer · push_back · rbegin · reference · rend · replace · reserve · resize · reverse_iterator · rfind · size · size_type · substr · swap · traits_type · value_type

class string {
public:
    typedef char_traits traits_type;
    typedef char_allocator allocator_type;
    typedef T0 iterator;
    typedef T1 const_iterator;
    typedef T2 size_type;
    typedef T3 difference_type;
    class const_reverse_iterator;
    class reverse_iterator;
    typedef allocator_type::pointer
        pointer;
    typedef allocator_type::const_pointer
        const_pointer;
    typedef allocator_type::reference
        reference;
    typedef allocator_type::const_reference
        const_reference;
    typedef allocator_type::value_type
        value_type;
    static const size_type npos = -1;
    string();
    explicit string(const allocator_type& al);
    string(const string& right);
    string(const string& right, size_type roff,
        size_type count = npos);
    string(const string& right, size_type roff,
        size_type count, const allocator_type& al);
    string(const value_type *ptr, size_type count);
    string(const value_type *ptr, size_type count,
        const allocator_type& al);
    string(const value_type *ptr);
    string(const value_type *ptr,
        const allocator_type& al);
    string(size_type count, value_type ch);
    string(size_type count, value_type ch,
        const allocator_type& al);
    string(const_iterator first,
        const_iterator last);
    string(const_iterator first,
        const_iterator last,
        const allocator_type& al);
    string& operator=(const string& right);
    string& operator=(const value_type *ptr);
    string& operator=(value_type ch);
    iterator begin();
    const_iterator begin() const;
    iterator end();
    const_iterator end() const;
    reverse_iterator rbegin();
    const_reverse_iterator rbegin() const;
    reverse_iterator rend();
    const_reverse_iterator rend() const;
    const_reference at(size_type off) const;
    reference at(size_type off);
    const_reference operator[](size_type off) const;
    reference operator[](size_type off);
    void push_back(value_type ch);
    const value_type *c_str() const;
    const value_type *data() const;
    size_type length() const;
    size_type size() const;
    size_type max_size() const;
    void resize(size_type newsize, value_type ch = value_type());
    size_type capacity() const;
    void reserve(size_type count = 0);
    bool empty() const;
    string& operator+=(const string& right);
    string& operator+=(const value_type *ptr);
    string& operator+=(value_type ch);

    string& append(const string& right);
    string& append(const string& right,
        size_type roff, size_type count);
    string& append(const value_type *ptr,
        size_type count);
    string& append(const value_type *ptr);
    string& append(size_type count, value_type ch);
    string& append(const_iterator first,
        const_iterator last);
    string& assign(const string& right);
    string& assign(const string& right,
        size_type roff, size_type count);
    string& assign(const value_type *ptr,
        size_type count);
    string& assign(const value_type *ptr);
    string& assign(size_type count, value_type ch);
    string& assign(const_iterator first,
        const_iterator last);
    string& insert(size_type off,
        const string& right);
    string& insert(size_type off,
        const string& right, size_type roff,
            size_type count);
    string& insert(size_type off,
        const value_type *ptr, size_type count);
    string& insert(size_type off,
        const value_type *ptr);
    string& insert(size_type off,
        size_type count, value_type ch);
    iterator insert(iterator where,
        value_type ch = value_type());
    void insert(iterator where, size_type count, value_type ch);
    void insert(iterator where,
        const_iterator first, const_iterator last);
    string& erase(size_type off = 0,
        size_type count = npos);
    iterator erase(iterator where);
    iterator erase(iterator first, iterator last);
    void clear();
    string& replace(size_type off, size_type n0,
        const string& right);
    string& replace(size_type off, size_type n0,
        const string& right, size_type roff,
            size_type count);
    string& replace(size_type off, size_type n0,
        const value_type *ptr, size_type count);
    string& replace(size_type off, size_type n0,
        const value_type *ptr);
    string& replace(size_type off, size_type n0,
        size_type count, value_type ch);
    string& replace(iterator first, iterator last,
        const string& right);
    string& replace(iterator first, iterator last,
        const value_type *ptr, size_type count);
    string& replace(iterator first, iterator last,
        const value_type *ptr);
    string& replace(iterator first, iterator last,
        size_type count, value_type ch);
    string& replace(iterator first, iterator last,
        const_iterator first2, const_iterator last2);
    size_type copy(value_type *ptr, size_type count,
        size_type off = 0) const;
    void swap(string& right);

    size_type find(const string& right,
        size_type off = 0) const;
    size_type find(const value_type *ptr, size_type off,
        size_type count) const;
    size_type find(const value_type *ptr,
        size_type off = 0) const;
    size_type find(value_type ch, size_type off = 0) const;
    size_type rfind(const string& right,
        size_type off = npos) const;
    size_type rfind(const value_type *ptr, size_type off,
        size_type count = npos) const;
    size_type rfind(const value_type *ptr,
        size_type off = npos) const;
    size_type rfind(value_type ch,
        size_type off = npos) const;
    size_type find_first_of(const string& right,
        size_type off = 0) const;
    size_type find_first_of(const value_type *ptr,
        size_type off, size_type count) const;
    size_type find_first_of(const value_type *ptr,
        size_type off = 0) const;
    size_type find_first_of(value_type ch,
        size_type off = 0) const;
    size_type find_last_of(const string& right,
        size_type off = npos) const;
    size_type find_last_of(const value_type *ptr,
        size_type off, size_type count = npos) const;
    size_type find_last_of(const value_type *ptr,
        size_type off = npos) const;
    size_type find_last_of(value_type ch,
        size_type off = npos) const;
    size_type find_first_not_of(const string& right,
        size_type off = 0) const;
    size_type find_first_not_of(const value_type *ptr,
        size_type off, size_type count) const;
    size_type find_first_not_of(const value_type *ptr,
        size_type off = 0) const;
    size_type find_first_not_of(value_type ch,
        size_type off = 0) const;
    size_type find_last_not_of(const string& right,
        size_type off = npos) const;
    size_type find_last_not_of(const value_type *ptr,
        size_type off, size_type count) const;
    size_type find_last_not_of(const value_type *ptr,
        size_type off = npos) const;
    size_type find_last_not_of(value_type ch,
        size_type off = npos) const;
    string substr(size_type off = 0,
        size_type count = npos) const;
    int compare(const string& right) const;
    int compare(size_type off, size_type n0,
        const string& right) const;
    int compare(size_type off, size_type n0,
        const string& right, size_type roff,
            size_type count) const;
    int compare(const value_type *ptr) const;
    int compare(size_type off, size_type n0,
        const value_type *ptr) const;
    int compare(size_type off, size_type n0,
        const value_type *ptr, size_type off) const;
    allocator_type get_allocator() const;
    };

The class describes an object that controls a varying-length sequence of elements of type char, also known as value_type. Various important properties of the elements in a string are described by the class char_traits, also known as traits_type.

The object allocates and frees storage for the sequence it controls through a stored allocator object of class char_allocator, also known as allocator_type. Note that the stored allocator object is not copied when the container object is assigned.

The sequences controlled by an object of class string are usually called strings. These objects should not be confused, however, with the null-terminated C strings used throughout the Standard C++ library.

Many member functions require an operand sequence of elements. You can specify such an operand sequence several ways:

ch -- one element with value ch
count, ch -- a repetition of count elements each with value ch
ptr -- a null-terminated sequence (such as a C string) beginning at ptr (which must not be a null pointer), where the terminating element is the value value_type() and is not part of the operand sequence
ptr, count -- a sequence of count elements beginning at ptr (which must not be a null pointer)
right -- the sequence specified by the string object right
right, roff, count -- the substring of the string object right with up to count elements (or through the end of the string, whichever comes first) beginning at position roff
first, last -- a sequence of elements delimited by the iterators first and last, in the range [first, last), which may overlap the sequence controlled by the string object whose member function is being called

If a position argument (such as roff above) is beyond the end of the string on a call to a string member function, the function reports an out-of-range error by throwing an object of class out_of_range.

If a function is asked to generate a sequence longer than max_size() elements, the function reports a length error by throwing an object of class length_error.

References, pointers, and iterators that designate elements of the controlled sequence can become invalid after any call to a function that alters the controlled sequence, or after the first call to the non-const member functions at, begin, end, operator[], rbegin, or rend. (The idea is to permit multiple strings to share the same representation until one string becomes a candidate for change, at which point that string makes a private copy of the representation, using a discipline called copy on write.)

`string::allocator_type`

typedef char_allocator allocator_type;

The type is a synonym for char_allocator.

`string::append`

string& append(const value_type *ptr);
string& append(const value_type *ptr,
    size_type count);
string& append(const string& right,
    size_type roff, size_type count);
string& append(const string& right);
string& append(size_type count, value_type ch);
string& append(const_iterator first,
    const_iterator last);

The member functions each append the operand sequence to the end of the sequence controlled by *this, then return *this.

`string::assign`

string& assign(const value_type *ptr);
string& assign(const value_type *ptr,
    size_type count);
string& assign(const string& right,
    size_type roff, size_type count);
string& assign(const string& right);
string& assign(size_type count, value_type ch);
string& assign(const_iterator first,
    const_iterator last);

The member functions each replace the sequence controlled by *this with the operand sequence, then return *this.

`string::at`

const_reference at(size_type off) const;
reference at(size_type off);

The member functions each return a reference to the element of the controlled sequence at position off, or report an out-of-range error.

`string::string`

string(const value_type *ptr);
string(const value_type *ptr,
    const allocator_type& al);
string(const value_type *ptr, size_type count);
string(const value_type *ptr, size_type count,
    const allocator_type& al);
string(const string& right);
string(const string& right, size_type roff,
    size_type count = npos);
string(const string& right, size_type roff,
    size_type count, const allocator_type& al);
string(size_type count, value_type ch);
string(size_type count, value_type ch,
    const allocator_type& al);
string();
explicit string(const allocator_type& al);
string(const_iterator first, const_iterator last);
string(const_iterator first, const_iterator last,
    const allocator_type& al);

All constructors store an allocator object and initialize the controlled sequence. The allocator object is the argument al, if present. For the copy constructor, it is right.get_allocator(). Otherwise, it is Alloc().

The controlled sequence is initialized to a copy of the operand sequence specified by the remaining operands. A constructor with no operand sequence specifies an empty initial controlled sequence.

`string::begin`

const_iterator begin() const;
iterator begin();

The member functions each return a random-access iterator that points at the first element of the sequence (or just beyond the end of an empty sequence).

`string::c_str`

const value_type *c_str() const;

The member function returns a pointer to a non-modifiable C string constructed by adding a terminating null element (value_type()) to the controlled sequence. Calling any non-const member function for *this can invalidate the pointer.

`string::capacity`

size_type capacity() const;

The member function returns the storage currently allocated to hold the controlled sequence, a value at least as large as size().

`string::clear`

void clear();

The member function calls erase( begin(), end()).

`string::compare`

int compare(const string& right) const;
int compare(size_type off, size_type n0,
    const string& right) const;
int compare(size_type off, size_type n0,
    const string& right, size_type roff, size_type count) const;
int compare(const value_type *ptr) const;
int compare(size_type off, size_type n0,
    const value_type *ptr) const;
int compare(size_type off, size_type n0,
    const value_type *ptr, size_type off) const;

The member functions each compare up to n0 elements of the controlled sequence beginning with position off, or the entire controlled sequence if these arguments are not supplied, to the operand sequence. Each function returns:

a negative value if the first differing element in the controlled sequence compares less than the corresponding element in the operand sequence (as determined by traits_type::compare), or if the two have a common prefix but the operand sequence is longer
zero if the two compare equal element by element and are the same length
a positive value otherwise

`string::const_iterator`

typedef T1 const_iterator;

The type describes an object that can serve as a constant random-access iterator for the controlled sequence. It is described here as a synonym for the implementation-defined type T1.

`string::const_pointer`

typedef allocator_type::const_pointer
    const_pointer;

The type is a synonym for allocator_type::const_pointer.

`string::const_reference`

typedef allocator_type::const_reference
    const_reference;

The type is a synonym for allocator_type::const_reference.

`string::const_reverse_iterator`

class const_reverse_iterator;

The type describes an object that can serve as a constant reverse iterator for the controlled sequence. You can, for example, access each of the elements in the controlled sequence in reverse order by writing:

    string::const_reverse_iterator rit;
    for (rit = rbegin(); rit != rend(); ++rit)
        process *rit

`string::copy`

size_type copy(value_type *ptr, size_type count,
    size_type off = 0) const;

The member function copies up to count elements from the controlled sequence, beginning at position off, to the array of value_type beginning at ptr. It returns the number of elements actually copied.

`string::data`

const value_type *data() const;

The member function returns a pointer to the first element of the sequence (or, for an empty sequence, a non-null pointer that cannot be dereferenced).

`string::difference_type`

typedef T3 difference_type;

The signed integer type describes an object that can represent the difference between the addresses of any two elements in the controlled sequence. It is described here as a synonym for the implementation-defined type T3.

`string::empty`

bool empty() const;

The member function returns true for an empty controlled sequence.

`string::end`

const_iterator end() const;
iterator end();

The member functions each return a random-access iterator that points just beyond the end of the sequence.

`string::erase`

iterator erase(iterator first, iterator last);
iterator erase(iterator where);
string& erase(size_type off = 0,
    size_type count = npos);

The first member function removes the elements of the controlled sequence in the range [first, last). The second member function removes the element of the controlled sequence pointed to by where. Both return an iterator that designates the first element remaining beyond any elements removed, or end() if no such element exists.

The third member function removes up to count elements of the controlled sequence beginning at position off, then returns *this.

`string::find`

size_type find(value_type ch, size_type off = 0) const;
size_type find(const value_type *ptr,
    size_type off = 0) const;
size_type find(const value_type *ptr, size_type off,
    size_type count) const;
size_type find(const string& right,
    size_type off = 0) const;

The member functions each find the first (lowest beginning position) subsequence in the controlled sequence, beginning on or after position off, that matches the operand sequence specified by the remaining operands. If it succeeds, it returns the position where the matching subsequence begins. Otherwise, the function returns npos.

`string::find_first_not_of`

size_type find_first_not_of(value_type ch,
    size_type off = 0) const;
size_type find_first_not_of(const value_type *ptr,
    size_type off = 0) const;
size_type find_first_not_of(const value_type *ptr,
    size_type off, size_type count) const;
size_type find_first_not_of(const string& right,
    size_type off = 0) const;

The member functions each find the first (lowest position) element of the controlled sequence, at or after position off, that matches none of the elements in the operand sequence specified by the remaining operands. If it succeeds, it returns the position. Otherwise, the function returns npos.

`string::find_first_of`

size_type find_first_of(value_type ch,
    size_type off = 0) const;
size_type find_first_of(const value_type *ptr,
    size_type off = 0) const;
size_type find_first_of(const value_type *ptr,
    size_type off, size_type count) const;
size_type find_first_of(const string& right,
    size_type off = 0) const;

The member functions each find the first (lowest position) element of the controlled sequence, at or after position off, that matches any of the elements in the operand sequence specified by the remaining operands. If it succeeds, it returns the position. Otherwise, the function returns npos.

`string::find_last_not_of`

size_type find_last_not_of(value_type ch,
    size_type off = npos) const;
size_type find_last_not_of(const value_type *ptr,
    size_type off = npos) const;
size_type find_last_not_of(const value_type *ptr,
    size_type off, size_type count) const;
size_type find_last_not_of(const string& right,
    size_type off = npos) const;

The member functions each find the last (highest position) element of the controlled sequence, at or before position off, that matches none of the elements in the operand sequence specified by the remaining operands. If it succeeds, it returns the position. Otherwise, the function returns npos.

`string::find_last_of`

size_type find_last_of(value_type ch,
    size_type off = npos) const;
size_type find_last_of(const value_type *ptr,
    size_type off = npos) const;
size_type find_last_of(const value_type *ptr,
    size_type off, size_type count = npos) const;
size_type find_last_of(const string& right,
    size_type off = npos) const;

The member functions each find the last (highest position) element of the controlled sequence, at or before position off, that matches any of the elements in the operand sequence specified by the remaining operands. If it succeeds, it returns the position. Otherwise, the function returns npos.

`string::get_allocator`

allocator_type get_allocator() const;

The member function returns the stored allocator object.

`string::insert`

string& insert(size_type off, const value_type *ptr);
string& insert(size_type off, const value_type *ptr,
    size_type count);
string& insert(size_type off,
    const string& right);
string& insert(size_type off,
    const string& right, size_type roff, size_type count);
string& insert(size_type off,
    size_type count, value_type ch);
iterator insert(iterator where,
    value_type ch = value_type());
void insert(iterator where,
    const_iterator first, const_iterator last);
void insert(iterator where, size_type count, value_type ch);

The member functions each insert, before position off or before the element pointed to by where in the controlled sequence, the operand sequence specified by the remaining operands. A function that returns a value returns *this.

`string::iterator`

typedef T0 iterator;

The type describes an object that can serve as a random-access iterator for the controlled sequence. It is described here as a synonym for the implementation-defined type T0.

`string::length`

size_type length() const;

The member function returns the length of the controlled sequence (same as size()).

`string::max_size`

size_type max_size() const;

The member function returns the length of the longest sequence that the object can control.

`string::npos`

static const size_type npos = -1;

The constant is the largest representable value of type size_type. It is assuredly larger than max_size(), hence it serves as either a very large value or as a special code.

`string::operator+=`

string& operator+=(value_type ch);
string& operator+=(const value_type *ptr);
string& operator+=(const string& right);

The operators each append the operand sequence to the end of the sequence controlled by *this, then return *this.

`string::operator=`

string& operator=(value_type ch);
string& operator=(const value_type *ptr);
string& operator=(const string& right);

The operators each replace the sequence controlled by *this with the operand sequence, then return *this.

`string::operator[]`

const_reference operator[](size_type off) const;
reference operator[](size_type off);

The member functions each return a reference to the element of the controlled sequence at position off. If that position is invalid, the behavior is undefined. Note, however, that cstr[cstr.size()] == 0 for the first member function.

`string::pointer`

typedef allocator_type::pointer
    pointer;

The type is a synonym for allocator_type::pointer.

`string::push_back`

void push_back(value_type ch);

The member function effectively calls insert( end(), ch).

`string::rbegin`

const_reverse_iterator rbegin() const;
reverse_iterator rbegin();

The member function returns a reverse iterator that points just beyond the end of the controlled sequence. Hence, it designates the beginning of the reverse sequence.

`string::reference`

typedef allocator_type::reference
    reference;

The type is a synonym for allocator_type::reference.

`string::rend`

const_reverse_iterator rend() const;
reverse_iterator rend();

The member functions each return a reverse iterator that points at the first element of the sequence (or just beyond the end of an empty sequence). Hence, the function designates the end of the reverse sequence.

`string::replace`

string& replace(size_type off, size_type n0,
    const value_type *ptr);
string& replace(size_type off, size_type n0,
    const value_type *ptr, size_type count);
string& replace(size_type off, size_type n0,
    const string& right);
string& replace(size_type off, size_type n0,
    const string& right, size_type roff, size_type count);
string& replace(size_type off, size_type n0,
    size_type count, value_type ch);
string& replace(iterator first, iterator last,
    const value_type *ptr);
string& replace(iterator first, iterator last,
    const value_type *ptr, size_type count);
string& replace(iterator first, iterator last,
    const string& right);
string& replace(iterator first, iterator last,
    size_type count, value_type ch);
string& replace(iterator first, iterator last,
    const_iterator first2, const_iterator last2);

The member functions each replace up to n0 elements of the controlled sequence beginning with position off, or the elements of the controlled sequence beginning with the one pointed to by first, up to but not including last. The replacement is the operand sequence specified by the remaining operands. The function then returns *this.

`string::reserve`

void reserve(size_type count = 0);

The member function ensures that capacity() henceforth returns at least count.

`string::resize`

void resize(size_type newsize, value_type ch = value_type());

The member function ensures that size() henceforth returns newsize. If it must make the controlled sequence longer, it appends elements with value ch. To make the controlled sequence shorter, the member function effectively calls erase(begin() + newsize, end()).

`string::reverse_iterator`

class reverse_iterator;

The type describes an object that can serve as a reverse iterator for the controlled sequence. You can, for example, access each of the elements in the controlled sequence in reverse order by writing:

    string::reverse_iterator rit;
    for (rit = rbegin(); rit != rend(); ++rit)
        process *rit

`string::rfind`

size_type rfind(value_type ch, size_type off = npos) const;
size_type rfind(const value_type *ptr,
    size_type off = npos) const;
size_type rfind(const value_type *ptr,
    size_type off, size_type count = npos) const;
size_type rfind(const string& right,
    size_type off = npos) const;

The member functions each find the last (highest beginning position) subsequence in the controlled sequence, beginning on or before position off, that matches the operand sequence specified by the remaining operands. If it succeeds, the function returns the position where the matching subsequence begins. Otherwise, it returns npos.

`string::size`

size_type size() const;

The member function returns the length of the controlled sequence.

`string::size_type`

typedef T2 size_type;

The unsigned integer type describes an object that can represent the length of any controlled sequence. It is described here as a synonym for the implementation-defined type T2.

`string::substr`

string substr(size_type off = 0,
    size_type count = npos) const;

The member function returns an object whose controlled sequence is a copy of up to count elements of the controlled sequence beginning at position off.

`string::swap`

void swap(string& right);

The member function swaps the controlled sequences between *this and str. If get_allocator() == right.get_allocator(), it does so in constant time, it throws no exceptions, and it invalidates no references, pointers, or iterators that designate elements in the two controlled sequences. Otherwise, it performs a number of element assignments and constructor calls proportional to the number of elements in the two controlled sequences.

`string::traits_type`

typedef char_traits traits_type;

The type is a synonym for char_traits.

`string::value_type`

typedef allocator_type::value_type
    value_type;

The type is a synonym for allocator_type::value_type.

`char_allocator`

class char_allocator {
public:
    char_allocator();
    pointer allocate(size_type count, const void *hint);
    void deallocate(pointer ptr, size_type count);
    size_type max_size() const;
    bool operator==(char_allocator& left,
        char_allocator& right) const;
    };

The class describes an object that manages storage allocation and freeing for arrays of objects of type char. An object of class char_allocator is the allocator object used by class string. It is used here primarily to minimize differences with full Standard C++.

`char_allocator::allocate`

pointer allocate(size_type count, const void *hint);

The member function allocates storage for an array of count elements of type char, by calling operator new(count). It returns a pointer to the allocated object. The hint argument is unused here. To supply no hint, use a null pointer argument instead.

`char_allocator::char_allocator`

char_allocator();

The constructor does nothing.

`char_allocator::deallocate`

void deallocate(pointer ptr, size_type count);

The member function frees storage for the array of count objects of type char beginning at ptr, by calling operator delete(ptr). The pointer ptr must have been earlier returned by a call to allocate for an allocator object that compares equal to *this, allocating an array object of the same size and type.

`char_allocator::max_size`

size_type max_size() const;

The member function returns the length of the longest sequence of elements of type char that an object of class char_allocator might be able to allocate.

`char_allocator::operator==`

bool operator==(char_allocator& left,
    char_allocator& right) const;

The operator returns true. (Two allocator objects should compare equal only if an object allocated through one can be deallocated through the other. If the value of one object is determined from another by assignment or by construction, the two object should compare equal.)

`char_traits`

class char_traits {
public:
    typedef char char_type;
    typedef int int_type;
    typedef streampos pos_type;
    typedef streamoff off_type;
    typedef mbstate_t state_type;
    static void assign(char_type& left, const char_type& right);
    static char_type *assign(char_type *first, size_t count,
        char_type ch);
    static bool eq(const char_type& left,
        const char_type& right);
    static bool lt(const char_type& left,
        const char_type& right);
    static int compare(const char_type *first1,
        const char_type *first2, size_t count);
    static size_t length(const char_type *first);
    static char_type *copy(char_type *first1,
        const char_type *first2, size_t count);
    static char_type *move(char_type *first1,
        const char_type *first2, size_t count);
    static const char_type *find(const char_type *first,
        size_t count, const char_type& ch);
    static char_type to_char_type(const int_type& meta);
    static int_type to_int_type(const char_type& ch);
    static bool eq_int_type(const int_type& left,
        const int_type& right);
    static int_type eof();
    static int_type not_eof(const int_type& meta);
    };

The class describes various character traits for type char. The class string as well as several iostreams classes, including ios, use this information to manipulate elements of type char.

None of the member functions of class char_traits may throw exceptions.

`char_traits::assign`

static void assign(char_type& left, const char_type& right);
static char_type *assign(char_type *first, size_t count,
    char_type ch);

The first static member function assigns right to left. The second static member function assigns ch to each element X[N] for N in the range [0, count).

`char_traits::char_type`

typedef char char_type;

The type is a synonym for char.

`char_traits::compare`

static int compare(const char_type *first1,
    const char_type *first2, size_t count);

The static member function compares the sequence of length count beginning at first1to the sequence of the same length beginning at first2. The function returns:

a negative value if the first differing element in first1 (as determined by eq) compares less than the corresponding element in first2 (as determined by lt)
zero if the two compare equal element by element
a positive value otherwise

`char_traits::copy`

static char_type *copy(char_type *first1, const char_type *first2,
    size_t count);

The static member function copies the sequence of count elements beginning at first2 to the array beginning at first1, then returns first1. The source and destination must not overlap.

`char_traits::eof`

static int_type eof();

The static member function returns a value that represents end-of-file (EOF).

`char_traits::eq`

static bool eq(const char_type& left, const char_type& right);

The static member function returns true if left compares equal to right.

`char_traits::eq_int_type`

static bool eq_int_type(const int_type& left,
    const int_type& right);

The static member function returns true if left compares equal to right.

`char_traits::find`

static const char_type *find(const char_type *first,
    size_t count, const char_type& ch);

The static member function determines the lowest N in the range [0, count) for which eq(first[N], ch) is true. If successful, it returns first + N. Otherwise, it returns a null pointer.

`char_traits::int_type`

typedef int int_type;

The type is a synonym for int.

`char_traits::length`

static size_t length(const char_type *first);

The static member function returns the number of elements N in the sequence beginning at first up to but not including the element first[N] which compares equal to char_type().

`char_traits::lt`

static bool lt(const char_type& left, const char_type& right);

The static member function returns true if left compares less than right.

`char_traits::move`

static char_type *move(char_type *first1, const char_type *first2,
    size_t count);

The static member function copies the sequence of count elements beginning at first2 to the array beginning at first1, then returns first1. The source and destination may overlap.

`char_traits::not_eof`

static int_type not_eof(const int_type& meta);

If !eq_int_type( eof(), meta), the static member function returns meta. Otherwise, it returns a value other than eof().

`char_traits::off_type`

typedef streamoff off_type;

The type is a synonym for streamoff.

`char_traits::pos_type`

typedef streampos pos_type;

The type is a synonym for streampos.

`char_traits::state_type`

typedef mbstate_t state_type;

The type is a synonym for mbstate_t.

`char_traits::to_char_type`

static char_type to_char_type(const int_type& meta);

The static member function returns meta represented as type Elem. A value of meta that cannot be so represented yields an unspecified result.

`char_traits::to_int_type`

static int_type to_int_type(const char_type& ch);

The static member function returns ch represented as type int_type. It must be possible to convert any value ch of type Elem to int_type (by evaluating meta = to_int_type(ch)) then back to Elem (by evaluating ch = to_char_type(meta)) and obtain a value that compares equal to ch.

`getline`

istream& getline(istream& istr,
    string& str);
istream& getline(istream& istr,
    string& str, char delim);

The first function returns getline(istr, str, istr.widen('\n')).

The second function replaces the sequence controlled by str with a sequence of elements extracted from the stream istr. In order of testing, extraction stops:

at end of file
after the function extracts an element that compares equal to delim, in which case the element is neither put back nor appended to the controlled sequence
after the function extracts str.max_size() elements, in which case the function calls setstate(ios_base::failbit).

If the function extracts no elements, it calls setstate(failbit). In any case, it returns istr.

`operator+`

string operator+(
    const string& left,
    const string& right);
string operator+(
    const string& left,
    const char *right);
string operator+(
    const string& left,
    char right);
string operator+(
    const char *left,
    const string& right);
string operator+(
    char left,
    const string& right);

The functions each overload operator+ to concatenate two objects of class string. All effectively return string(left).append(right).

`operator!=`

bool operator!=(
    const string& left,
    const string& right);
bool operator!=(
    const string& left,
    const char *right);
bool operator!=(
    const char *left,
    const string& right);

The functions each overload operator!= to compare two objects of class string. All effectively return string(left).compare(right) != 0.

`operator==`

bool operator==(
    const string& left,
    const string& right);
bool operator==(
    const string& left,
    const char *right);
bool operator==(
    const char *left,
    const string& right);

The functions each overload operator== to compare two objects of class string. All effectively return string(left).compare(right) == 0.

`operator<`

bool operator<(
    const string& left,
    const string& right);
bool operator<(
    const string& left,
    const char *right);
bool operator<(
    const char *left,
    const string& right);

The functions each overload operator< to compare two objects of class string. All effectively return string(left).compare(right) < 0.

`operator<<`

ostream& operator<<(
    ostream& ostr,
    const string& str);

The function is a formatted output functions that overloads operator<< to determine the length len = str.size() of the sequence controlled by str, and insert the sequence. If len < ostr.width(), then the function also inserts a repetition of ostr.width() - len fill characters. The repetition precedes the sequence if (ostr.flags() & adjustfield != left. Otherwise, the repetition follows the sequence. The function returns ostr.

`operator<=`

bool operator<=(
    const string& left,
    const string& right);
bool operator<=(
    const string& left,
    const char *right);
bool operator<=(
    const char *left,
    const string& right);

The functions each overload operator<= to compare two objects of class string. All effectively return string(left).compare(right) <= 0.

`operator>`

bool operator>(
    const string& left,
    const string& right);
bool operator>(
    const string& left,
    const char *right);
bool operator>(
    const char *left,
    const string& right);

The functions each overload operator> to compare two objects of class string. All effectively return string(left).compare(right) > 0.

`operator>=`

bool operator>=(
    const string& left,
    const string& right);
bool operator>=(
    const string& left,
    const char *right);
bool operator>=(
    const char *left,
    const string& right);

The functions each overload operator>= to compare two objects of class string. All effectively return string(left).compare(right) >= 0.

`operator>>`

istream& operator>>(
    istream& istr,
    string& str);

The template function overloads operator>> to replace the sequence controlled by str with a sequence of elements extracted from the stream istr. Extraction stops:

at end of file
after the function extracts istr.width() elements, if that value is nonzero
after the function extracts istr.max_size() elements
after the function extracts an element ch for which isspace(ch) is true, in which case the character is put back

If the function extracts no elements, it calls setstate(ios_base::failbit). In any case, it calls istr.width(0) and returns *this.

`swap`

template<class Tr, class Alloc>
    void swap(
        string& left,
        string& right);

The template function executes left.swap(right).

See also the Table of Contents and the Index.

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