[#boost-urls-grammar-hexdig_value]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::xref:boost/urls/grammar.adoc[grammar]::hexdig&lowbar;value
:relfileprefix: ../../../
:mrdocs:

Return the decimal value of a hex character

== Synopsis

Declared in `&lt;https://www.github.com/boostorg/url/blob/develop/include/boost/url/grammar/hexdig_chars.hpp#L117[boost&sol;url&sol;grammar&sol;hexdig&lowbar;chars&period;hpp]&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
signed char
hexdig&lowbar;value(char ch) noexcept;
----

== Description

This function returns the decimal value of a hexadecimal character, or &hyphen;1 if the argument is not a valid hexadecimal digit&period;

== BNF
[,cpp]
----
HEXDIG      = DIGIT
            / "A" / "B" / "C" / "D" / "E" / "F"
            / "a" / "b" / "c" / "d" / "e" / "f"
----
== Return Value

The decimal value or &hyphen;1

== Parameters

[cols=2]
|===
| Name
| Description
| *ch*
| The character to check
|===


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