:relfileprefix: ../../../../
[#boost-urls-grammar-lut_chars-08friend-02]

= xref:boost.adoc[pass:[boost]]::xref:boost/urls.adoc[pass:[urls]]::xref:boost/urls/grammar.adoc[pass:[grammar]]::operator+


Return the union of two character sets.


== Synopsis

Declared in header `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/grammar/lut_chars.hpp#L299[boost/url/grammar/lut_chars.hpp,window=blank_]>`

[source,cpp,subs="verbatim,macros,-callouts"]
----
friend
constexpr
xref:boost/urls/grammar/lut_chars.adoc[lut_chars]
operator+(
    xref:boost/urls/grammar/lut_chars.adoc[lut_chars] const& cs0,
    xref:boost/urls/grammar/lut_chars.adoc[lut_chars] const& cs1) noexcept;
----

== Description


This function returns a new character
set which contains all of the characters
in `cs0` as well as all of the characters
in `cs`.

=== Example

This creates a character set which
includes all letters and numbers
[,cpp]
----
constexpr lut_chars alpha_chars(
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz");

constexpr lut_chars alnum_chars = alpha_chars + "0123456789";
----

=== Complexity

Constant.