[diff.cpp03.strings]

# Annex C (informative) Compatibility [[diff]](./#diff)

## C.6 C++ and ISO C++ 2003 [[diff.cpp03]](diff.cpp03#strings)

### C.6.11 [[strings]](strings "27 Strings library"): strings library [diff.cpp03.strings]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/compatibility.tex#L2535)

**Affected subclause:** [[string.classes]](string.classes)  


**Change:** basic_string requirements no longer allow reference-counted
strings[.](#1.sentence-1)

  


**Rationale:** Invalidation is subtly different with reference-counted strings[.](#1.sentence-2)

This change regularizes behavior[.](#1.sentence-3)

  


**Effect on original feature:** Valid C++ 2003 code may execute differently in this revision of C++[.](#1.sentence-4)

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/compatibility.tex#L2545)

**Affected subclause:** [[string.require]](string.require)  


**Change:** Loosen basic_string invalidation rules[.](#2.sentence-1)

  


**Rationale:** Allow small-string optimization[.](#2.sentence-2)

  


**Effect on original feature:** Valid C++ 2003 code may execute differently in this revision of C++[.](#2.sentence-3)

Some const member functions, such as data and c_str,
no longer invalidate iterators[.](#2.sentence-4)