[edit]Syntax

[edit]Explanation

In the types listed in the table above,N is the number of encoded code units, which is determinedbelow.

Ordinary and UTF-8(since C++11) string literals are collectively referred to as narrow string literals.

Evaluating a string literal results in a string literal object with staticstorage duration. Whether all string literals are stored innonoverlapping objects and whether successive evaluations of a string literal yield the same or a different object is unspecified.

The effect of attempting to modify a string literal object is undefined.

bool b="bar"==3+"foobar";// can be true or false, unspecified constchar* pc="Hello";char* p=const_cast<char*>(pc);p[0]='M';// undefined behavior

// OK: contains one backslash,// equivalent to "\\"R"(\)"; // OK: contains four \n pairs,// equivalent to "\\n\\n\\n\\n"R"(\n\n\n\n)"; // OK: contains one close-parenthesis, two double-quotes and one open-parenthesis,// equivalent to ")\"\"("R"-()""()-"; // OK: equivalent to "\n)\\\na\"\"\n"R"a()\a"")a"; // OK: equivalent to "x = \"\"\\y\"\""R"(x = ""\y"")"; // R"<<(-_-)>>"; // Error: begin and end delimiters do not match// R"-()-"-()-"; // Error: )-" appears in the middle and terminates the literal

[edit]Initialization

String literal objects are initialized with the sequence of code unit values corresponding to the string literal’s sequence ofs-char s andr-char s(since C++11), plus a terminating null character (U+0000), in order as follows:

[edit]Concatenation

Adjacent string literals are concatenated attranslation phase 6 (after preprocessing):

• If the two string literals are of the samekind, the concatenated string literal is also of that kind.

"Hello, ""world!"// at phase 6, the 2 string literals form "Hello, world!" L"Δx = %"PRId16// at phase 4, PRId16 expands to "d"// at phase 6, L"Δx = %" and "d" form L"Δx = %d"

1. ↑No known implementation supports such concatenation.

[edit]Unevaluated strings

The following contexts expect a string literal, but do not evaluate it:

• language linkage specification

[edit]Notes

String literals can be used toinitialize character arrays. If an array is initialized likechar str[]="foo";,str will contain a copy of the string"foo".

A string literal is not necessarily a null-terminated character sequence: if a string literal has embedded null characters, it represents an array which contains more than one string.

constchar* p="abc\0def";// std::strlen(p) == 3, but the array has size 8

If a valid hexadecimal digit follows a hexadecimal escape sequence in a string literal, it would fail to compile as an invalid escape sequence. String concatenation can be used as a workaround:

//const char* p = "\xfff"; // error: hexadecimal escape sequence out of rangeconstchar* p="\xff""f";// OK: the literal is const char[3] holding {'\xff','f','\0'}

[edit]Example

#include <iostream> // array1 and array2 contains the same values:char array1[]="Foo""bar";char array2[]={'F','o','o','b','a','r','\0'}; constchar* s1= R"foo(Hello  World)foo";// same asconstchar* s2="\nHello\n  World\n";// same asconstchar* s3="\n""Hello\n""  World\n"; constwchar_t* s4= L"ABC" L"DEF";// OK, same asconstwchar_t* s5= L"ABCDEF";constchar32_t* s6= U"GHI""JKL";// OK, same asconstchar32_t* s7= U"GHIJKL";constchar16_t* s9="MN" u"OP""QR";// OK, same asconstchar16_t* sA= u"MNOPQR"; // const auto* sB = u"Mixed" U"Types";// before C++23 may or may not be supported by// the implementation; ill-formed since C++23 constwchar_t* sC= LR"--(STUV)--";// OK, raw string literal int main(){std::cout<< array1<<' '<< array2<<'\n'<< s1<< s2<< s3<<std::endl;std::wcout<< s4<<' '<< s5<<' '<< sC<<std::endl;}

Foobar Foobar Hello  World Hello  World Hello  World ABCDEF ABCDEF STUV

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

1. ↑P1854R4 was accepted as a DR later, overriding this resolution.

[edit]References

[edit]See also

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