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# Escape sequences

From cppreference.com
< c‎ | language

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

The following escape sequences are available. ISO C requires a diagnostic if the backslash is followed by any character not listed here:

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` | Unicode character that is not in the basic character set. May result in several characters. | code point `U+nnnn`
`\Unnnnnnnn` | Unicode character that is not in the basic character set. May result in several characters. | code point `U+nnnnnnnn`

### [edit] 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 length 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 or character constant (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 "??/"

### [edit] Example

Run this code

    #include <stdio.h>

    int main(void)
    {
        printf("This\nis\na\ntest\n\nShe said, \"How are you?\"\n");
    }

Output:

    This
    is
    a
    test

    She said, "How are you?"

### [edit] References

- C11 standard (ISO/IEC 9899:2011):

  - 5.2.2 Character display semantics (p: 24-25)

  - 6.4.4.4 Character constants (p: 67-70)

- C99 standard (ISO/IEC 9899:1999):

  - 5.2.2 Character display semantics (p: 19-20)

  - 6.4.4.4 Character constants (p: 59-61)

- C89/C90 standard (ISO/IEC 9899:1990):

  - 2.2.2 Character display semantics

  - 3.1.3.4 Character constants

### [edit] See also

- ASCII chart

C++ documentation for Escape sequence

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