[#absl-CUnescape-06]
= xref:absl.adoc[absl]::CUnescape
:relfileprefix: ../
:mrdocs:

Unescapes a `source` string and copies it into `dest`, rewriting C‐style escape sequences (https://en.cppreference.com/w/cpp/language/escape) into their proper code point equivalents, returning `true` if successful.

== Synopsis

Declared in `<absl/strings/escaping.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
bool
CUnescape(
    std::string_view source,
    std::string* dest,
    std::string* error);
----

== Description

The following unescape sequences can be handled:

* ASCII escape sequences (' ','r','', etc.) to their ASCII equivalents * Octal escape sequences ('nnn') to byte nnn. The unescaped value must resolve to a single byte or an error will occur. E.g. values greater than 0xff will produce an error. * Hexadecimal escape sequences ('xnn') to byte nn. While an arbitrary number of following digits are allowed, the unescaped value must resolve to a single byte or an error will occur. E.g. 'x0045' is equivalent to 'x45', but 'x1234' will produce an error. * Unicode escape sequences ('unnnn' for exactly four hex digits or 'Unnnnnnnn' for exactly eight hex digits, which will be encoded in UTF‐8. (E.g., `u2019` unescapes to the three bytes 0xE2, 0x80, and 0x99).

If any errors are encountered, this function returns `false`, leaving the `dest` output parameter in an unspecified state, and stores the first encountered error in `error`. To disable error reporting, set `error` to `nullptr` or use the overload with no error reporting below.

Example:

std::string s = "foo\rbar\nbaz\t"; std::string unescaped_s; if (!absl::CUnescape(s, &unescaped_s)) { ... } EXPECT_EQ(unescaped_s, "foorbarnbazt");

== Return Value

`true` on success, `false` if an error was encountered.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *source*
| The escaped string to unescape.
| *dest*
| The output string that receives the unescaped result.
| *error*
| Receives the first error encountered, or `nullptr` to disable error reporting.
|===


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