[#boost-urls-grammar-digit_chars]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/grammar.adoc[grammar]::digit_chars
:relfileprefix: ../../../
:mrdocs:

The set of decimal digits

== Synopsis

Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/grammar/digit_chars.hpp#L76[boost/url/grammar/digit_chars.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
constexpr /* implementation-defined */ digit_chars = {};
----

== Description

== Example
Character sets are used with rules and the functions xref:boost/urls/grammar/find_if.adoc[`find_if`] and xref:boost/urls/grammar/find_if_not.adoc[`find_if_not`].

[,cpp]
----
system::result< core::string_view > rv = parse( "2022", token_rule( digit_chars ) );
----
== BNF
[,cpp]
----
DIGIT       = %x30-39
            ; 0-9
----
== Specification
* https://datatracker.ietf.org/doc/html/rfc5234#appendix-B.1[]

== See Also

xref:boost/urls/grammar/find_if.adoc[`find&lowbar;if`], xref:boost/urls/grammar/find_if_not.adoc[`find&lowbar;if&lowbar;not`], xref:boost/urls/grammar/parse-09.adoc[`parse`], xref:boost/urls/grammar/token_rule.adoc[`token&lowbar;rule`]&period;


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