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


Return the decimal value of a hex character

== Synopsis


Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/grammar/hexdig_chars.hpp#L163[boost/url/grammar/hexdig_chars.hpp]>`

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

== Description


This function returns the decimal    value of a hexadecimal character,    or ‐1 if the argument is not a    valid hexadecimal digit.


=== BNF

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


== Return Value


The decimal value or ‐1



== Parameters


|===
| Name | Description

| *ch*
| The character to check


|===



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