Escape sequences

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

C++ language

 

Expressions

General

value categories (lvalue, rvalue, xvalue)

order of evaluation (sequence points)

constant expressions

unevaluated expressions

primary expressions

lambda-expression(C++11)

Literals

integer literals

floating-point literals

boolean literals

character literals including escape sequences

string literals

null pointer literal(C++11)

user-defined literal(C++11)

Operators

Assignment operators: a=b, a+=b, a-=b, a*=b, a/=b, a%=b, a&=b, a|=b, a^=b, a<<=b, a>>=

Increment and decrement: ++a, --a, a++, a--

Arithmetic operators: +a, -a, a+b, a-b, a*b, a/b, a%b, ~a, a&b, a|b, a^b, a<<b, a>>b

Logical operators: a||b, a&&b, !a

Comparison operators: a==b, a!=b, a<b, a>b, a<=b, a>=b

Member access operators: a[b], *a, &a, a->b, a.b, a->*b, a.*b

Other operators: a(...), a,b, a?b:c

Alternative representations of operators

Precedence and associativity

Fold expression(C++17)

new-expression

delete-expression

throw-expression

alignof

sizeof

sizeof...(C++11)

typeid

noexcept(C++11)

Operator overloading

Conversions

Implicit conversions

const_cast

static_cast

reinterpret_cast

dynamic_cast

Explicit conversions (T)a, T(a)

User-defined conversion

 

Escape sequences are used to represent certain special characters within string literals and character literals.

The following escape sequences are available (extra escape sequences may be provided with implementation-defined semantics):

Escape sequence	Description	Representation
\'	single quote	byte 0x27 in ASCII encoding
\"	double quote	byte 0x22 in ASCII encoding
\?	question mark	byte 0x3f in ASCII encoding
\\	backslash	byte 0x5c in ASCII encoding
\a	audible bell	byte 0x07 in ASCII encoding
\b	backspace	byte 0x08 in ASCII encoding
\f	form feed - new page	byte 0x0c in ASCII encoding
\n	line feed - new line	byte 0x0a in ASCII encoding
\r	carriage return	byte 0x0d in ASCII encoding
\t	horizontal tab	byte 0x09 in ASCII encoding
\v	vertical tab	byte 0x0b in ASCII encoding
\nnn	arbitrary octal value	byte nnn
\xnn	arbitrary hexadecimal value	byte nn
\unnnn	universal character name (arbitrary Unicode value); may result in several characters	code point U+nnnn
\Unnnnnnnn	universal character name (arbitrary Unicode value); may result in several characters	code point U+nnnnnnnn

Notes

Of the octal escape sequences, \0 is the most useful because it represents the terminating null character in null-terminated strings.

The new-line character \n has special meaning when used in text mode I/O: it is converted to the OS-specific newline byte or byte sequence.

Octal escape sequences have a limit of three octal digits, but terminate at the first character that is not a valid octal digit if encountered sooner.

Hexadecimal escape sequences have no length limit and terminate at the first character that is not a valid hexadecimal digit. If the value represented by a single hexadecimal escape sequence does not fit the range of values represented by the character type used in this string literal (char, char16_t, char32_t, or wchar_t), the result is unspecified.

A universal character name in a narrow string literal or a 16-bit string literal may map to more than one character, e.g. \U0001f34c is 4 char code units in UTF-8 (\xF0\x9F\x8D\x8C) and 2 char16_t code units in UTF-16 (\uD83C\uDF4C)).

The question mark escape sequence \? is used to prevent trigraphs from being interpreted inside string literals: a string such as "??/" is compiled as "\", but if the second question mark is escaped, as in "?\?/", it becomes "??/"

Example

Run this code

#include <cstdio>
 
int main()
{
    std::printf("This\nis\na\ntest\n\nShe said, \"How are you?\"\n");
}

Output:

This
is
a
test
 
She said, "How are you?"

See also

• ASCII chart