在 PdfLatex 中使用 \newcommand 包含分類顏色

Question 1

我們可以將計數器與 newcommand 巨集結合使用來將來產生可以為文字著色的新命令。下面給出一個簡單的例子：

%define colours pre document 

\newcounter{cnt}
\newcommand{\cdef}[1]{%
 \stepcounter{cnt}%
\xglobal \definecolor{#1}{HTML}{#1}
\expandafter\newcommand\csname c\Roman{cnt}\endcsname{\textcolor{#1}}%
}


%start the main body
\begin{document}



% Define list of colours to run here, reference with \cI \cII \cIII etc... 
\cdef{00CCFF}
\cdef{99CC99}


%write away within the document
\cI {test c1} and then \cII{test c2}

這會產生以下結果：

Answer

我們可以將計數器與 newcommand 巨集結合使用來將來產生可以為文字著色的新命令。下面給出一個簡單的例子：

%define colours pre document 

\newcounter{cnt}
\newcommand{\cdef}[1]{%
 \stepcounter{cnt}%
\xglobal \definecolor{#1}{HTML}{#1}
\expandafter\newcommand\csname c\Roman{cnt}\endcsname{\textcolor{#1}}%
}


%start the main body
\begin{document}



% Define list of colours to run here, reference with \cI \cII \cIII etc... 
\cdef{00CCFF}
\cdef{99CC99}


%write away within the document
\cI {test c1} and then \cII{test c2}

這會產生以下結果：

Question 2

您可以建立一個由數字引用的清單：

\documentclass{article}
\usepackage{xparse}
\usepackage{xcolor}

\ExplSyntaxOn
\NewDocumentCommand{\colorlist}{m}
 {
  \clist_map_inline:nn {#1}
   {
    \seq_gput_right:Nn \g_colorlist_list_seq { ##1 }
   }
 }

\NewDocumentCommand{\usecolor}{mm}
 {
  \textcolor[HTML]{ \seq_item:Nn \g_colorlist_list_seq { #1 } } { #2 }
 }

\seq_new:N \g_colorlist_list_seq

\ExplSyntaxOff

\colorlist{828282,FF0000,00FF00}

\begin{document}

\usecolor{1}{text in first color}

\usecolor{2}{text in second color}

\usecolor{3}{text in third color}

\end{document}

請注意，xcolor需要以字串形式給出 HTML 顏色六十六進制數字，大寫或小寫。

Answer

您可以建立一個由數字引用的清單：

\documentclass{article}
\usepackage{xparse}
\usepackage{xcolor}

\ExplSyntaxOn
\NewDocumentCommand{\colorlist}{m}
 {
  \clist_map_inline:nn {#1}
   {
    \seq_gput_right:Nn \g_colorlist_list_seq { ##1 }
   }
 }

\NewDocumentCommand{\usecolor}{mm}
 {
  \textcolor[HTML]{ \seq_item:Nn \g_colorlist_list_seq { #1 } } { #2 }
 }

\seq_new:N \g_colorlist_list_seq

\ExplSyntaxOff

\colorlist{828282,FF0000,00FF00}

\begin{document}

\usecolor{1}{text in first color}

\usecolor{2}{text in second color}

\usecolor{3}{text in third color}

\end{document}

請注意，xcolor需要以字串形式給出 HTML 顏色六十六進制數字，大寫或小寫。

Question 3

你請求命令\c。
\cLaTeX 2e 核心已經定義了用變音符號來傳送信件。
因此，在下面的範例中，\ColorNumber定義了一個命令。

以下是您自己提供的答案的變體：

\documentclass{article}
\usepackage{xcolor}

\makeatletter

% define colours pre document 

\newcommand\MYNAMESPACEDefinedColorTotal{0}%
\newcommand\cdef[1]{%
 \@bsphack
 \begingroup
 \@tempcnta=\MYNAMESPACEDefinedColorTotal\relax
 \advance\@tempcnta by 1\relax
 \xdef\MYNAMESPACEDefinedColorTotal{\number\@tempcnta}%
 \endgroup
 \xglobal\definecolor{%
   MYNAMESPACEDefinedColor\MYNAMESPACEDefinedColorTotal%
 }{HTML}{#1}%
 \@esphack
}

\newcommand\ColorNumber[1]{\textcolor{MYNAMESPACEDefinedColor#1}}%

\makeatother

%start the main body
\begin{document}

\cdef{00CCFF}
\cdef{99CC99}

%write away within the document
\ColorNumber{1}{test c1} and then \ColorNumber{2}{test c2}


\end{document}

這是您作為自己的答案提供的另一種變體，這裡\ColorNumber的第一個參數通過參數文本中的 - 符號用大括號分隔#1#- 這更接近您在問題中要求的符號：

\documentclass{article}
\usepackage{xcolor}

\makeatletter

% define colours pre document 

\newcommand\MYNAMESPACEDefinedColorTotal{0}%
\newcommand\cdef[1]{%
 \@bsphack
 \begingroup
 \@tempcnta=\MYNAMESPACEDefinedColorTotal\relax
 \advance\@tempcnta by 1\relax
 \xdef\MYNAMESPACEDefinedColorTotal{\number\@tempcnta}%
 \endgroup
 \xglobal\definecolor{%
   MYNAMESPACEDefinedColor\MYNAMESPACEDefinedColorTotal%
 }{HTML}{#1}%
 \@esphack
}

\newcommand\ColorNumber{}%
\def\ColorNumber#1#{\textcolor{MYNAMESPACEDefinedColor#1}}%

\makeatother

%start the main body
\begin{document}

\cdef{00CCFF}
\cdef{99CC99}

%write away within the document
\ColorNumber1{test c1} and then \ColorNumber2{test c2}


\end{document}

這是另一種變體，其中數字後面的空格被刪除：

\documentclass{article}
\usepackage{xcolor}

\makeatletter
%%=============================================================================
%% Paraphernalia:
%%    \UD@firstoftwo, \UD@secondoftwo,\UD@CheckWhetherNull,
%%=============================================================================
\newcommand\UD@firstoftwo[2]{#1}%
\newcommand\UD@secondoftwo[2]{#2}%
%%-----------------------------------------------------------------------------
%% Check whether argument is empty:
%%.............................................................................
%% \UD@CheckWhetherNull{<Argument which is to be checked>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is empty>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is not empty>}%
%%
%% The gist of this macro comes from Robert R. Schneck's \ifempty-macro:
%% <https://groups.google.com/forum/#!original/comp.text.tex/kuOEIQIrElc/lUg37FmhA74J>
\newcommand\UD@CheckWhetherNull[1]{%
  \romannumeral0\expandafter\UD@secondoftwo\string{\expandafter
  \UD@secondoftwo\expandafter{\expandafter{\string#1}\expandafter
  \UD@secondoftwo\string}\expandafter\UD@firstoftwo\expandafter{\expandafter
  \UD@secondoftwo\string}\expandafter\expandafter\UD@firstoftwo{ }{}%
  \UD@secondoftwo}{\expandafter\expandafter\UD@firstoftwo{ }{}\UD@firstoftwo}%
}%
%%-----------------------------------------------------------------------------
%% \UD@RemoveTrailingSpaces{<argument>} removes trailing spaces from <argument>.
%% !!!! <argument> must not contain the token \UD@seldom !!!!
%%.............................................................................
\begingroup
\newcommand\UD@RemoveTrailingSpaces[1]{%
  \endgroup
  \newcommand\UD@RemoveTrailingSpaces[1]{%
    \romannumeral0%
    \UD@trimtrailspaceloop.##1\UD@seldom#1\UD@seldom\UD@seldom#1{.##1}%
  }%
  \newcommand\UD@trimtrailspaceloop{}%
  \long\def\UD@trimtrailspaceloop##1#1\UD@seldom##2\UD@seldom#1##3{%
    \UD@CheckWhetherNull{##2}{%
      \UD@firstoftwo{ }##3%
    }{%
      \UD@trimtrailspaceloop##1\UD@seldom#1\UD@seldom\UD@seldom#1{##1}%
    }%
  }%
}%
\UD@RemoveTrailingSpaces{ }%

% define colours pre document 

\newcommand\MYNAMESPACEDefinedColorTotal{0}%
\newcommand\cdef[1]{%
 \@bsphack
 \begingroup
 \@tempcnta=\MYNAMESPACEDefinedColorTotal\relax
 \advance\@tempcnta by 1\relax
 \xdef\MYNAMESPACEDefinedColorTotal{\number\@tempcnta}%
 \endgroup
 \xglobal\definecolor{%
   MYNAMESPACEDefinedColor\MYNAMESPACEDefinedColorTotal%
 }{HTML}{#1}%
 \@esphack
}

\newcommand\ColorNumber{}%
\def\ColorNumber#1#{%
  \expandafter\expandafter\expandafter\@ColorNumber
  \expandafter\expandafter\expandafter{\UD@RemoveTrailingSpaces{#1}}%
}%
\newcommand*\@ColorNumber[1]{%
  \textcolor{MYNAMESPACEDefinedColor#1}%
}%

\makeatother

%start the main body
\begin{document}

\cdef{00CCFF}
\cdef{99CC99}

%write away within the document
\ColorNumber1{test c1} and then \ColorNumber2{test c2}

\ColorNumber 1 {test c1} and then \ColorNumber 2 {test c2}

\end{document}

如果顏色清單很小，您可以使用類似的方法\UD@PassKthArg提取該清單的第 K 個元素並將其傳遞給\textcolor— 這樣您甚至可以調用，\textcolor甚至無需透過以下方式定義顏色\definecolor：

\documentclass{article}
\usepackage{xcolor}%

\makeatletter
%% Code for \UD@PassKthArg
%%=============================================================================
%% Paraphernalia:
%%    \UD@firstoftwo, \UD@secondoftwo, UD@Exchange, \UD@PassFirstToSecond, 
%%    \UD@CheckWhetherNull, UD@CheckWhetherBlank
%%=============================================================================
\newcommand\UD@firstoftwo[2]{#1}%
\newcommand\UD@secondoftwo[2]{#2}%
\newcommand\UD@Exchange[2]{#2#1}%
\newcommand\UD@PassFirstToSecond[2]{#2{#1}}%
%%-----------------------------------------------------------------------------
%% Check whether argument is empty:
%%.............................................................................
%% \UD@CheckWhetherNull{<Argument which is to be checked>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is empty>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is not empty>}%
%%
%% The gist of this macro comes from Robert R. Schneck's \ifempty-macro:
%% <https://groups.google.com/forum/#!original/comp.text.tex/kuOEIQIrElc/lUg37FmhA74J>
\newcommand\UD@CheckWhetherNull[1]{%
  \romannumeral0\expandafter\UD@secondoftwo\string{\expandafter
  \UD@secondoftwo\expandafter{\expandafter{\string#1}\expandafter
  \UD@secondoftwo\string}\expandafter\UD@firstoftwo\expandafter{\expandafter
  \UD@secondoftwo\string}\expandafter\expandafter\UD@firstoftwo{ }{}%
  \UD@secondoftwo}{\expandafter\expandafter\UD@firstoftwo{ }{}\UD@firstoftwo}%
}%
%%------------------------------------------------------------------------------
%% Check whether argument is blank (empty or only spaces):
%%..............................................................................
%% -- Take advantage of the fact that TeX discards space tokens when
%%    "fetching" _un_delimited arguments: --
%% \UD@CheckWhetherBlank{<Argument which is to be checked>}%
%%                      {<Tokens to be delivered in case that
%%                        argument which is to be checked is blank>}%
%%                      {<Tokens to be delivered in case that argument
%%                        which is to be checked is not blank}%
\newcommand\UD@CheckWhetherBlank[1]{%
  \romannumeral\expandafter\expandafter\expandafter\UD@secondoftwo
  \expandafter\UD@CheckWhetherNull\expandafter{\UD@firstoftwo#1{}.}%
}%
%%=============================================================================
%% Put K-th inner undelimited argument behind sequence of tokens:
%%
%% \UD@PassKthArg{<tokens>}{<ErrorTokens>}{<integer K>}{<list of undelimited args>} 
%% 
%% In case there is no K-th argument in <list of indelimited args> : 
%%   Does deliver <ErrorTokens>.
%% In case there is a K-th argument in <list of indelimited args> : 
%%   Does place that K-th argument with one level of braces removed behind <tokens>.
%%
%% Examples:
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{0}{ABCDE} yields: ERROR
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{3}{ABCDE} yields:  ELEMENT-C
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{3}{AB{CD}E} yields:  ELEMENT-CD
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{4}{{001}{002}{003}{004}{005}} yields: ELEMENT-004
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{6}{{001}{002}{003}} yields: ERROR
%% 
%%=============================================================================
\newcommand\UD@PassKthArg[3]{%
  \romannumeral0%
  % #1: <Tokens>
  % #2: <ErrorTokens>
  % #3: <integer number K>
  \expandafter\UD@PassKthArgCheck
  \expandafter{\romannumeral\number\number#3 000}{#1}{#2}%
}%
\newcommand\UD@PassKthArgCheck[4]{%
  % #1 - <K letters m>
  % #2 - <Tokens>
  % #3 - <ErrorTokens>
  % #4 - <list>
  \UD@CheckWhetherNull{#1}{ #3}{%
    \expandafter\UD@PassKthArgLoop\expandafter{\UD@firstoftwo{}#1}{#4}{#2}{#3}%
  }%
}%
\newcommand\UD@PassKthArgLoop[4]{%
  % #1 - <letters m in an amount that corresponds to the number
  %       of arguments trailing the to-be-kept argument>
  % #2 - <list>
  % #3 - <Tokens>
  % #4 - <ErrorTokens>
  \UD@CheckWhetherBlank{#2}{ #4}{%
    \UD@CheckWhetherNull{#1}{%
      \UD@ExtractFirstArgLoop{#2\UD@SelDOm}{#3}%
    }{%
      \expandafter\UD@PassFirstToSecond\expandafter{\UD@firstoftwo{}#2}%
      {\expandafter\UD@PassKthArgLoop\expandafter{\UD@firstoftwo{}#1}}%
      {#3}{#4}%
    }%
  }%
}%
\newcommand\UD@RemoveTillUD@SelDOm{}%
\long\def\UD@RemoveTillUD@SelDOm#1#2\UD@SelDOm{{#1}}%
\newcommand\UD@ExtractFirstArgLoop[2]{%
  \expandafter\UD@CheckWhetherNull\expandafter{\UD@firstoftwo{}#1}%
  {\UD@Exchange#1{ #2}}%
  {\expandafter\UD@ExtractFirstArgLoop\expandafter{\UD@RemoveTillUD@SelDOm#1}{#2}}%
}%
%% End of code for \UD@PassKthArg

\newcommand\ColorNumber[1]{%
  \expandafter\UD@PassFirstToSecond\expandafter{\Mycolorlist}{\UD@PassKthArg{\textcolor}{%
    \GenericError{%
      \@spaces\@spaces\@spaces\@spaces\@spaces\@spaces\@spaces\@spaces\space\space\space
    }{%
       Error with command \string\ColorNumber: \string\Mycolorlist\space does not have a%
       \MessageBreak color-specification-element #1%
    }{Color will not be changed.}{Specify the number of an element which is in the list.}%
  }{#1}}%
}%
\makeatother

\definecolor{myweirdcolor}{HTML}{800080}% PURPLE

% List of color-specifications.
% Each specification must be nested in braces.
% You are not bound to the HTML-Hex-Code-model.

\newcommand\Mycolorlist{%
  {[HTML]{00CCFF}}% CYAN
  {[HTML]{C0C0C0}}% SILVER
  {[HTML]{808080}}% GRAY
  {[HTML]{000000}}% BLACK
  {[rgb]{1,0,0}}  % RED
  {[HTML]{800000}}% MAROON
  {[HTML]{FFFF00}}% YELLOW
  {[HTML]{808000}}% OLIVE
  {[HTML]{00FF00}}% LIME
  {[HTML]{008000}}% GREEN
  {[HTML]{00FFFF}}% AQUA
  {[HTML]{008080}}% TEAL
  {[HTML]{0000FF}}% BLUE
  {[HTML]{000080}}% NAVY
  {[HTML]{FF00FF}}% FUCHSIA
  {{myweirdcolor}}% PURPLE
}

\begin{document}
\noindent
\ColorNumber{1}{test C1 - CYAN}\\
\ColorNumber{2}{test C2 - SILVER}\\
\ColorNumber{3}{test C3 - GRAY}\\
\ColorNumber{4}{test C4 - BLACK}\\
\ColorNumber{5}{test C5 - RED}\\
\ColorNumber{6}{test C6 - MAROON}\\
\ColorNumber{7}{test C7 - YELLOW}\\
\ColorNumber{8}{test C8 - OLIVE}\\
\ColorNumber{9}{test C9 - LIME}\\
\ColorNumber{10}{test C10 - GREEN}\\
\ColorNumber{11}{test C11 - AQUA}\\
\ColorNumber{12}{test C12 - TEAL}\\
\ColorNumber{13}{test C13 - BLUE}\\
\ColorNumber{14}{test C14 - NAVY}\\
\ColorNumber{15}{test C15 - FUCHSIA}\\
\ColorNumber{16}{test C16 - PURPLE}\\
%\ColorNumber{17}{test C17 - ERROR}\\
%\ColorNumber{0}{test C0 - ERROR}
\end{document}

結合上面的方法（其中數字後面的尾隨空格被刪除）與 \UD@PassKthArg用於提取第 K 個元素的方法 where 會產生：

\documentclass{article}
\usepackage{xcolor}%

\makeatletter
%% Code for \UD@PassKthArg
%%=============================================================================
%% Paraphernalia:
%%    \UD@firstoftwo, \UD@secondoftwo, UD@Exchange, \UD@PassFirstToSecond, 
%%    \UD@CheckWhetherNull, UD@CheckWhetherBlank
%%=============================================================================
\newcommand\UD@firstoftwo[2]{#1}%
\newcommand\UD@secondoftwo[2]{#2}%
\newcommand\UD@Exchange[2]{#2#1}%
\newcommand\UD@PassFirstToSecond[2]{#2{#1}}%
%%-----------------------------------------------------------------------------
%% Check whether argument is empty:
%%.............................................................................
%% \UD@CheckWhetherNull{<Argument which is to be checked>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is empty>}%
%%                     {<Tokens to be delivered in case that argument
%%                       which is to be checked is not empty>}%
%%
%% The gist of this macro comes from Robert R. Schneck's \ifempty-macro:
%% <https://groups.google.com/forum/#!original/comp.text.tex/kuOEIQIrElc/lUg37FmhA74J>
\newcommand\UD@CheckWhetherNull[1]{%
  \romannumeral0\expandafter\UD@secondoftwo\string{\expandafter
  \UD@secondoftwo\expandafter{\expandafter{\string#1}\expandafter
  \UD@secondoftwo\string}\expandafter\UD@firstoftwo\expandafter{\expandafter
  \UD@secondoftwo\string}\expandafter\expandafter\UD@firstoftwo{ }{}%
  \UD@secondoftwo}{\expandafter\expandafter\UD@firstoftwo{ }{}\UD@firstoftwo}%
}%
%%------------------------------------------------------------------------------
%% Check whether argument is blank (empty or only spaces):
%%..............................................................................
%% -- Take advantage of the fact that TeX discards space tokens when
%%    "fetching" _un_delimited arguments: --
%% \UD@CheckWhetherBlank{<Argument which is to be checked>}%
%%                      {<Tokens to be delivered in case that
%%                        argument which is to be checked is blank>}%
%%                      {<Tokens to be delivered in case that argument
%%                        which is to be checked is not blank}%
\newcommand\UD@CheckWhetherBlank[1]{%
  \romannumeral\expandafter\expandafter\expandafter\UD@secondoftwo
  \expandafter\UD@CheckWhetherNull\expandafter{\UD@firstoftwo#1{}.}%
}%
%%==============================================================================
%% Put K-th inner undelimited argument behind sequence of tokens:
%%
%% \UD@PassKthArg{<tokens>}{<ErrorTokens>}{<integer K>}{<list of undelimited args>} 
%% 
%% In case there is no K-th argument in <list of indelimited args> : 
%%   Does deliver <ErrorTokens>.
%% In case there is a K-th argument in <list of indelimited args> : 
%%   Does place that K-th argument with one level of braces removed behind <tokens>.
%%
%% Examples:
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{0}{ABCDE} yields: ERROR
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{3}{ABCDE} yields:  ELEMENT-C
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{3}{AB{CD}E} yields:  ELEMENT-CD
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{4}{{001}{002}{003}{004}{005}} yields: ELEMENT-004
%%
%%   \UD@PassKthArg{ELEMENT-}{ERROR}{6}{{001}{002}{003}} yields: ERROR
%% 
%%=============================================================================
\newcommand\UD@PassKthArg[3]{%
  \romannumeral0%
  % #1: <Tokens>
  % #2: <ErrorTokens>
  % #3: <integer number K>
  \expandafter\UD@PassKthArgCheck
  \expandafter{\romannumeral\number\number#3 000}{#1}{#2}%
}%
\newcommand\UD@PassKthArgCheck[4]{%
  % #1 - <K letters m>
  % #2 - <Tokens>
  % #3 - <ErrorTokens>
  % #4 - <list>
  \UD@CheckWhetherNull{#1}{ #3}{%
    \expandafter\UD@PassKthArgLoop\expandafter{\UD@firstoftwo{}#1}{#4}{#2}{#3}%
  }%
}%
\newcommand\UD@PassKthArgLoop[4]{%
  % #1 - <letters m in an amount that corresponds to the number
  %       of arguments trailing the to-be-kept argument>
  % #2 - <list>
  % #3 - <Tokens>
  % #4 - <ErrorTokens>
  \UD@CheckWhetherBlank{#2}{ #4}{%
    \UD@CheckWhetherNull{#1}{%
      \UD@ExtractFirstArgLoop{#2\UD@SelDOm}{#3}%
    }{%
      \expandafter\UD@PassFirstToSecond\expandafter{\UD@firstoftwo{}#2}%
      {\expandafter\UD@PassKthArgLoop\expandafter{\UD@firstoftwo{}#1}}%
      {#3}{#4}%
    }%
  }%
}%
\newcommand\UD@RemoveTillUD@SelDOm{}%
\long\def\UD@RemoveTillUD@SelDOm#1#2\UD@SelDOm{{#1}}%
\newcommand\UD@ExtractFirstArgLoop[2]{%
  \expandafter\UD@CheckWhetherNull\expandafter{\UD@firstoftwo{}#1}%
  {\UD@Exchange#1{ #2}}%
  {\expandafter\UD@ExtractFirstArgLoop\expandafter{\UD@RemoveTillUD@SelDOm#1}{#2}}%
}%
%% End of code for \UD@PassKthArg
%%==============================================================================
%% \UD@RemoveTrailingSpaces{<argument>} removes trailing spaces from <argument>.
%% !!!! <argument> must not contain the token \UD@seldom !!!!
%%==============================================================================
\begingroup
\newcommand\UD@RemoveTrailingSpaces[1]{%
  \endgroup
  \newcommand\UD@RemoveTrailingSpaces[1]{%
    \romannumeral0%
    \UD@trimtrailspaceloop.##1\UD@seldom#1\UD@seldom\UD@seldom#1{.##1}%
  }%
  \newcommand\UD@trimtrailspaceloop{}%
  \long\def\UD@trimtrailspaceloop##1#1\UD@seldom##2\UD@seldom#1##3{%
    \UD@CheckWhetherNull{##2}{%
      \UD@firstoftwo{ }##3%
    }{%
      \UD@trimtrailspaceloop##1\UD@seldom#1\UD@seldom\UD@seldom#1{##1}%
    }%
  }%
}%
\UD@RemoveTrailingSpaces{ }%
%% End of code for \UD@RemoveTrailingSpaces

\newcommand\ColorNumber{}%
\def\ColorNumber#1#{%
  \expandafter\expandafter\expandafter\@ColorNumber
  \expandafter\expandafter\expandafter{\UD@RemoveTrailingSpaces{#1}}%
}%
\newcommand\@ColorNumber[1]{%
  \expandafter\UD@PassFirstToSecond\expandafter{\Mycolorlist}{\UD@PassKthArg{\textcolor}{%
    \GenericError{%
      \@spaces\@spaces\@spaces\@spaces\@spaces\@spaces\@spaces\@spaces\space\space\space
    }{%
       Error with command \string\ColorNumber: \string\Mycolorlist\space does not have a%
       \MessageBreak color-specification-element #1%
    }{Color will not be changed.}{Specify the number of an element which is in the list.}%
  }{#1}}%
}%
\makeatother

\definecolor{myweirdcolor}{HTML}{800080}% PURPLE

% List of color-specifications.
% Each specification must be nested in braces.
% You are not bound to the HTML-Hex-Code-model.

\newcommand\Mycolorlist{%
  {[HTML]{00CCFF}}% CYAN
  {[HTML]{C0C0C0}}% SILVER
  {[HTML]{808080}}% GRAY
  {[HTML]{000000}}% BLACK
  {[rgb]{1,0,0}}  % RED
  {[HTML]{800000}}% MAROON
  {[HTML]{FFFF00}}% YELLOW
  {[HTML]{808000}}% OLIVE
  {[HTML]{00FF00}}% LIME
  {[HTML]{008000}}% GREEN
  {[HTML]{00FFFF}}% AQUA
  {[HTML]{008080}}% TEAL
  {[HTML]{0000FF}}% BLUE
  {[HTML]{000080}}% NAVY
  {[HTML]{FF00FF}}% FUCHSIA
  {{myweirdcolor}}% PURPLE
}

\begin{document}
\noindent
\ColorNumber1{test C1 - CYAN}\\
\ColorNumber2{test C2 - SILVER}\\
\ColorNumber3{test C3 - GRAY}\\
\ColorNumber4{test C4 - BLACK}\\
\ColorNumber5{test C5 - RED}\\
\ColorNumber6{test C6 - MAROON}\\
\ColorNumber7{test C7 - YELLOW}\\
\ColorNumber8{test C8 - OLIVE}\\
\ColorNumber9{test C9 - LIME}\\
\ColorNumber10{test C10 - GREEN}\\
\ColorNumber11{test C11 - AQUA}\\
\ColorNumber12{test C12 - TEAL}\\
\ColorNumber13{test C13 - BLUE}\\
\ColorNumber14{test C14 - NAVY}\\
\ColorNumber15{test C15 - FUCHSIA}\\
\ColorNumber16{test C16 - PURPLE}\\
%\ColorNumber17{test C17 - ERROR}\\
%\ColorNumber0{test C0 - ERROR}
\end{document}

Answer