[string.require]

# 27 Strings library [[strings]](./#strings)

## 27.4 String classes [[string.classes]](string.classes#string.require)

### 27.4.3 Class template basic_string [[basic.string]](basic.string#string.require)

#### 27.4.3.2 General requirements [string.require]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/strings.tex#L2363)

If any operation would cause size() to
exceed max_size(), that operation throws an
exception object of type length_error[.](#1.sentence-1)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/strings.tex#L2368)

If any member function or operator of basic_string throws an exception, that
function or operator has no other effect on the basic_string object[.](#2.sentence-1)

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/strings.tex#L2372)

Every object of typebasic_string<charT, traits, Allocator> uses an object of typeAllocator to allocate and free storage for the contained charT objects as needed[.](#3.sentence-1)

The Allocator object used is
obtained as described in [[container.reqmts]](container.reqmts "23.2.2.2 Container requirements")[.](#3.sentence-2)

In every specialization basic_string<charT, traits, Allocator>,
the type traits shall meet
the character traits requirements ([[char.traits]](char.traits "27.2 Character traits"))[.](#3.sentence-3)

[*Note [1](#note-1)*:

Every specialization basic_string<charT, traits, Allocator> is
an allocator-aware container ([[container.alloc.reqmts]](container.alloc.reqmts "23.2.2.5 Allocator-aware containers")),
but does not use the allocator's construct and destroy member functions ([[container.requirements.pre]](container.requirements.pre "23.2.1 Preamble"))[.](#3.sentence-4)

The program is ill-formed ifAllocator​::​value_type is not the same type as charT[.](#3.sentence-5)

— *end note*]

[*Note [2](#note-2)*:

The program is ill-formed if traits​::​char_type is not the same type as charT[.](#3.sentence-6)

— *end note*]

[4](#4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/strings.tex#L2394)

References, pointers, and iterators referring to the elements of abasic_string sequence may be
invalidated by the following uses of that basic_string object:

- [(4.1)](#4.1)

  Passing as an argument to any standard library function taking a reference to non-constbasic_string as an argument[.](#4.1.sentence-1)[212](#footnote-212 "For example, as an argument to non-member functions swap() ([string.special]), operator>>() ([string.io]), and getline() ([string.io]), or as an argument to basic_­string​::​swap().")

- [(4.2)](#4.2)

  Calling non-const member functions, exceptoperator[],at,data,front,back,begin,rbegin,end,
andrend[.](#4.2.sentence-1)

[212)](#footnote-212)[212)](#footnoteref-212)

For example, as an argument to non-member
functions swap() ([[string.special]](string.special "27.4.4.3 swap")),operator>>() ([[string.io]](string.io "27.4.4.4 Inserters and extractors")), and getline() ([[string.io]](string.io "27.4.4.4 Inserters and extractors")), or as
an argument to basic_string​::​swap()[.](#footnote-212.sentence-1)