21 Strings library [strings]

21.3 String classes [string.classes]

21.3.3 Class template basic_­string [basic.string]

21.3.3.7 Modifiers [string.modifiers]

21.3.3.7.1 basic_­string​::​operator+= [string.op.append]

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constexpr basic_string& operator+=(const basic_string& str);
1
#
Effects: Equivalent to: return append(str);
🔗
template<class T> constexpr basic_string& operator+=(const T& t);
2
#
Constraints:
  • (2.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (2.2)
    is_­convertible_­v<const T&, const charT*> is false.
3
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return append(sv);
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constexpr basic_string& operator+=(const charT* s);
4
#
Effects: Equivalent to: return append(s);
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constexpr basic_string& operator+=(charT c);
5
#
Effects: Equivalent to: return append(size_­type{1}, c);
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constexpr basic_string& operator+=(initializer_list<charT> il);
6
#
Effects: Equivalent to: return append(il);

21.3.3.7.2 basic_­string​::​append [string.append]

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constexpr basic_string& append(const basic_string& str);
1
#
Effects: Equivalent to: return append(str.data(), str.size());
🔗
constexpr basic_string& append(const basic_string& str, size_type pos, size_type n = npos);
2
#
Effects: Equivalent to: return append(basic_string_view<charT, traits>(str).substr(pos, n));
🔗
template<class T> constexpr basic_string& append(const T& t);
3
#
Constraints:
  • (3.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (3.2)
    is_­convertible_­v<const T&, const charT*> is false.
4
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return append(sv.data(), sv.size());
🔗
template<class T> constexpr basic_string& append(const T& t, size_type pos, size_type n = npos);
5
#
Constraints:
  • (5.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (5.2)
    is_­convertible_­v<const T&, const charT*> is false.
6
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return append(sv.substr(pos, n));
🔗
constexpr basic_string& append(const charT* s, size_type n);
7
#
Preconditions: [s, s + n) is a valid range.
8
#
Effects: Appends a copy of the range [s, s + n) to the string.
9
#
Returns: *this.
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constexpr basic_string& append(const charT* s);
10
#
Effects: Equivalent to: return append(s, traits​::​length(s));
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constexpr basic_string& append(size_type n, charT c);
11
#
Effects: Appends n copies of c to the string.
12
#
Returns: *this.
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template<class InputIterator> constexpr basic_string& append(InputIterator first, InputIterator last);
13
#
Constraints: InputIterator is a type that qualifies as an input iterator ([container.requirements.general]).
14
#
Effects: Equivalent to: return append(basic_­string(first, last, get_­allocator()));
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constexpr basic_string& append(initializer_list<charT> il);
15
#
Effects: Equivalent to: return append(il.begin(), il.size());
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constexpr void push_back(charT c);
16
#
Effects: Equivalent to append(size_­type{1}, c).

21.3.3.7.3 basic_­string​::​assign [string.assign]

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constexpr basic_string& assign(const basic_string& str);
1
#
Effects: Equivalent to: return *this = str;
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constexpr basic_string& assign(basic_string&& str) noexcept(allocator_traits<Allocator>::propagate_on_container_move_assignment::value || allocator_traits<Allocator>::is_always_equal::value);
2
#
Effects: Equivalent to: return *this = std​::​move(str);
🔗
constexpr basic_string& assign(const basic_string& str, size_type pos, size_type n = npos);
3
#
Effects: Equivalent to: return assign(basic_string_view<charT, traits>(str).substr(pos, n));
🔗
template<class T> constexpr basic_string& assign(const T& t);
4
#
Constraints:
  • (4.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (4.2)
    is_­convertible_­v<const T&, const charT*> is false.
5
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return assign(sv.data(), sv.size());
🔗
template<class T> constexpr basic_string& assign(const T& t, size_type pos, size_type n = npos);
6
#
Constraints:
  • (6.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (6.2)
    is_­convertible_­v<const T&, const charT*> is false.
7
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return assign(sv.substr(pos, n));
🔗
constexpr basic_string& assign(const charT* s, size_type n);
8
#
Preconditions: [s, s + n) is a valid range.
9
#
Effects: Replaces the string controlled by *this with a copy of the range [s, s + n).
10
#
Returns: *this.
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constexpr basic_string& assign(const charT* s);
11
#
Effects: Equivalent to: return assign(s, traits​::​length(s));
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constexpr basic_string& assign(initializer_list<charT> il);
12
#
Effects: Equivalent to: return assign(il.begin(), il.size());
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constexpr basic_string& assign(size_type n, charT c);
13
#
Effects: Equivalent to: clear(); resize(n, c); return *this;
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template<class InputIterator> constexpr basic_string& assign(InputIterator first, InputIterator last);
14
#
Constraints: InputIterator is a type that qualifies as an input iterator ([container.requirements.general]).
15
#
Effects: Equivalent to: return assign(basic_­string(first, last, get_­allocator()));

21.3.3.7.4 basic_­string​::​insert [string.insert]

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constexpr basic_string& insert(size_type pos, const basic_string& str);
1
#
Effects: Equivalent to: return insert(pos, str.data(), str.size());
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constexpr basic_string& insert(size_type pos1, const basic_string& str, size_type pos2, size_type n = npos);
2
#
Effects: Equivalent to: return insert(pos1, basic_string_view<charT, traits>(str), pos2, n);
🔗
template<class T> constexpr basic_string& insert(size_type pos, const T& t);
3
#
Constraints:
  • (3.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (3.2)
    is_­convertible_­v<const T&, const charT*> is false.
4
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return insert(pos, sv.data(), sv.size());
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template<class T> constexpr basic_string& insert(size_type pos1, const T& t, size_type pos2, size_type n = npos);
5
#
Constraints:
  • (5.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (5.2)
    is_­convertible_­v<const T&, const charT*> is false.
6
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return insert(pos1, sv.substr(pos2, n));
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constexpr basic_string& insert(size_type pos, const charT* s, size_type n);
7
#
Preconditions: [s, s + n) is a valid range.
8
#
Effects: Inserts a copy of the range [s, s + n) immediately before the character at position pos if pos < size(), or otherwise at the end of the string.
9
#
Returns: *this.
10
#
Throws:
  • (10.1)
    out_­of_­range if pos > size(),
  • (10.2)
    length_­error if n > max_­size() - size(), or
  • (10.3)
    any exceptions thrown by allocator_­traits<Allocator>​::​allocate.
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constexpr basic_string& insert(size_type pos, const charT* s);
11
#
Effects: Equivalent to: return insert(pos, s, traits​::​length(s));
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constexpr basic_string& insert(size_type pos, size_type n, charT c);
12
#
Effects: Inserts n copies of c before the character at position pos if pos < size(), or otherwise at the end of the string.
13
#
Returns: *this
14
#
Throws:
  • (14.1)
    out_­of_­range if pos > size(),
  • (14.2)
    length_­error if n > max_­size() - size(), or
  • (14.3)
    any exceptions thrown by allocator_­traits<Allocator>​::​allocate.
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constexpr iterator insert(const_iterator p, charT c);
15
#
Preconditions: p is a valid iterator on *this.
16
#
Effects: Inserts a copy of c at the position p.
17
#
Returns: An iterator which refers to the inserted character.
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constexpr iterator insert(const_iterator p, size_type n, charT c);
18
#
Preconditions: p is a valid iterator on *this.
19
#
Effects: Inserts n copies of c at the position p.
20
#
Returns: An iterator which refers to the first inserted character, or p if n == 0.
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template<class InputIterator> constexpr iterator insert(const_iterator p, InputIterator first, InputIterator last);
21
#
Constraints: InputIterator is a type that qualifies as an input iterator ([container.requirements.general]).
22
#
Preconditions: p is a valid iterator on *this.
23
#
Effects: Equivalent to insert(p - begin(), basic_­string(first, last, get_­allocator())).
24
#
Returns: An iterator which refers to the first inserted character, or p if first == last.
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constexpr iterator insert(const_iterator p, initializer_list<charT> il);
25
#
Effects: Equivalent to: return insert(p, il.begin(), il.end());

21.3.3.7.5 basic_­string​::​erase [string.erase]

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constexpr basic_string& erase(size_type pos = 0, size_type n = npos);
1
#
Effects: Determines the effective length xlen of the string to be removed as the smaller of n and size() - pos.
Removes the characters in the range [begin() + pos, begin() + pos + xlen).
2
#
Returns: *this.
3
#
Throws: out_­of_­range if pos > size().
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constexpr iterator erase(const_iterator p);
4
#
Preconditions: p is a valid dereferenceable iterator on *this.
5
#
Effects: Removes the character referred to by p.
6
#
Returns: An iterator which points to the element immediately following p prior to the element being erased.
If no such element exists, end() is returned.
7
#
Throws: Nothing.
🔗
constexpr iterator erase(const_iterator first, const_iterator last);
8
#
Preconditions: first and last are valid iterators on *this.
[first, last) is a valid range.
9
#
Effects: Removes the characters in the range [first, last).
10
#
Returns: An iterator which points to the element pointed to by last prior to the other elements being erased.
If no such element exists, end() is returned.
11
#
Throws: Nothing.
🔗
constexpr void pop_back();
12
#
Preconditions: !empty().
13
#
Effects: Equivalent to erase(end() - 1).
14
#
Throws: Nothing.

21.3.3.7.6 basic_­string​::​replace [string.replace]

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constexpr basic_string& replace(size_type pos1, size_type n1, const basic_string& str);
1
#
Effects: Equivalent to: return replace(pos1, n1, str.data(), str.size());
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constexpr basic_string& replace(size_type pos1, size_type n1, const basic_string& str, size_type pos2, size_type n2 = npos);
2
#
Effects: Equivalent to: return replace(pos1, n1, basic_string_view<charT, traits>(str).substr(pos2, n2));
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template<class T> constexpr basic_string& replace(size_type pos1, size_type n1, const T& t);
3
#
Constraints:
  • (3.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (3.2)
    is_­convertible_­v<const T&, const charT*> is false.
4
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return replace(pos1, n1, sv.data(), sv.size());
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template<class T> constexpr basic_string& replace(size_type pos1, size_type n1, const T& t, size_type pos2, size_type n2 = npos);
5
#
Constraints:
  • (5.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (5.2)
    is_­convertible_­v<const T&, const charT*> is false.
6
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return replace(pos1, n1, sv.substr(pos2, n2));
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constexpr basic_string& replace(size_type pos1, size_type n1, const charT* s, size_type n2);
7
#
Preconditions: [s, s + n2) is a valid range.
8
#
Effects: Determines the effective length xlen of the string to be removed as the smaller of n1 and size() - pos1.
If size() - xlen >= max_­size() - n2 throws length_­error.
Otherwise, the function replaces the characters in the range [begin() + pos1, begin() + pos1 + xlen) with a copy of the range [s, s + n2).
9
#
Returns: *this.
10
#
Throws:
  • (10.1)
    out_­of_­range if pos1 > size(),
  • (10.2)
    length_­error if the length of the resulting string would exceed max_­size(), or
  • (10.3)
    any exceptions thrown by allocator_­traits<Allocator>​::​allocate.
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constexpr basic_string& replace(size_type pos, size_type n, const charT* s);
11
#
Effects: Equivalent to: return replace(pos, n, s, traits​::​length(s));
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constexpr basic_string& replace(size_type pos1, size_type n1, size_type n2, charT c);
12
#
Effects: Determines the effective length xlen of the string to be removed as the smaller of n1 and size() - pos1.
If size() - xlen >= max_­size() - n2 throws length_­error.
Otherwise, the function replaces the characters in the range [begin() + pos1, begin() + pos1 + xlen) with n2 copies of c.
13
#
Returns: *this.
14
#
Throws:
  • (14.1)
    out_­of_­range if pos1 > size(),
  • (14.2)
    length_­error if the length of the resulting string would exceedmax_­size(), or
  • (14.3)
    any exceptions thrown by allocator_­traits<Allocator>​::​allocate.
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constexpr basic_string& replace(const_iterator i1, const_iterator i2, const basic_string& str);
15
#
Effects: Equivalent to: return replace(i1, i2, basic_­string_­view<charT, traits>(str));
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template<class T> constexpr basic_string& replace(const_iterator i1, const_iterator i2, const T& t);
16
#
Constraints:
  • (16.1)
    is_­convertible_­v<const T&, basic_­string_­view<charT, traits>> is true and
  • (16.2)
    is_­convertible_­v<const T&, const charT*> is false.
17
#
Preconditions: [begin(), i1) and [i1, i2) are valid ranges.
18
#
Effects: Equivalent to: basic_string_view<charT, traits> sv = t; return replace(i1 - begin(), i2 - i1, sv.data(), sv.size());
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constexpr basic_string& replace(const_iterator i1, const_iterator i2, const charT* s, size_type n);
19
#
Effects: Equivalent to: return replace(i1, i2, basic_­string_­view<charT, traits>(s, n));
🔗
constexpr basic_string& replace(const_iterator i1, const_iterator i2, const charT* s);
20
#
Effects: Equivalent to: return replace(i1, i2, basic_­string_­view<charT, traits>(s));
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constexpr basic_string& replace(const_iterator i1, const_iterator i2, size_type n, charT c);
21
#
Preconditions: [begin(), i1) and [i1, i2) are valid ranges.
22
#
Effects: Equivalent to: return replace(i1 - begin(), i2 - i1, n, c);
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template<class InputIterator> constexpr basic_string& replace(const_iterator i1, const_iterator i2, InputIterator j1, InputIterator j2);
23
#
Constraints: InputIterator is a type that qualifies as an input iterator ([container.requirements.general]).
24
#
Effects: Equivalent to: return replace(i1, i2, basic_­string(j1, j2, get_­allocator()));
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constexpr basic_string& replace(const_iterator i1, const_iterator i2, initializer_list<charT> il);
25
#
Effects: Equivalent to: return replace(i1, i2, il.begin(), il.size());

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

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constexpr size_type copy(charT* s, size_type n, size_type pos = 0) const;
1
#
Effects: Equivalent to: return basic_­string_­view<charT, traits>(*this).copy(s, n, pos);
[Note 1:
This does not terminate s with a null object.
— end note]

21.3.3.7.8 basic_­string​::​swap [string.swap]

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constexpr void swap(basic_string& s) noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value || allocator_traits<Allocator>::is_always_equal::value);
1
#
Preconditions: allocator_­traits<Allocator>​::​propagate_­on_­container_­swap​::​value is true or get_­allocator() == s.get_­allocator().
2
#
Postconditions: *this contains the same sequence of characters that was in s, s contains the same sequence of characters that was in *this.
3
#
Throws: Nothing.
4
#
Complexity: Constant time.