Escape sequences

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

# Notes

\0 is the most commonly used octal escape sequence, 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 representation, usually a byte or byte sequence. Some systems mark their lines with length fields instead.

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, char8_t,(since C++20)char16_t, char32_t,(since C++11)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 code unit, e.g. \U0001f34c is 4 char code units in UTF-8 (\xF0\x9F\x8D\x8C) and 2 char16_t code units in UTF-16 (\xD83C\xDF4C).

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 “??/”. As trigraphs have been removed from C++, the question mark escape sequence is no longer necessary. It is preserved for compatibility with C++14 (and former revisions) and C.(since C++17)

# Example

#include <iostream>
 
int main()
{
    std::cout << "This\nis\na\ntest\n\n";
    std::cout << "She said, \"Sells she seashells on the seashore?\"\n";
}

# Defect reports

# See also

• ASCII chart
• C documentation