\ifthenelse 中的字符串比较

Question 1

更新：已添加强制 xinttools 方法

有两个问题。第一个问题是\isinfrom 包xifthen没有展开它的第二个参数，这里是\dbline。第二个问题是\isin 使用的 LaTeX 内核\in@无法处理\par标记；但 TeX 总是会\par在通过的文件输入末尾附加一个标记\read，除非 \endlinechar 设置为 -1。

第一个问题可以通过定义一个\isinxp扩展其第二个参数的包装器来解决。第二个问题（假设\endlinechar不是 -1）通过在读取行之后和测试之前测试文件末尾来解决。

\documentclass[12pt, a4paper]{article}
\usepackage{filecontents}

\begin{filecontents*}{cities.txt}
A;London
B;Berlin
C;Paris
\end{filecontents*}

\usepackage{xstring}
\usepackage{xifthen}

% star form as anyhow \isin is declared short, and furthermore
% uses internally \in@ from the LaTeX kernel which is short
\newcommand*{\isinxp}[2]{\expandafter\isinxpp\expandafter{#2}{#1}}
\newcommand*{\isinxpp}[2]{\isin {#2}{#1}}

\begin{document}\thispagestyle{empty}

\newread\dbcities
\openin\dbcities=cities.txt

We start here:

\loop
    \read\dbcities to \dbline 
% (testing)   \texttt{\meaning\dbline}
\unless\ifeof\dbcities
    \ifthenelse{\isinxp{A}{\dbline}}
    {\StrCut{\dbline}{;}{\colA}{\colB}
    \colA: \colB \\}
    {}
\repeat

\closein\dbcities

\end{document}

字符串比较 ifthen

强制性新工具方法：

（我已经修正了键匹配，因为搜索BB会返回带有B键的数据行的误报。请注意，包含BB键的数据行在查找时返回正值B是预期的事情，正如 OP 所使用的那样\isin。）

\documentclass[12pt, a4paper]{article}
\usepackage{filecontents}
\begin{filecontents*}{\jobname.dat}
A;London
  B;   Berlin
BB; Hamburg
 C  ;  Paris
 A ;  London again
D;Roma
\end{filecontents*}

\usepackage{xinttools}

\newread\datastream

% to issue warnings if command names already in use, then one knows one
% has to change them (depens on loaded packages)
\newcommand {\onedataline}{}
\newcommand {\printdatakey}{}
\newcommand {\printdatatestkey}{}
\newcommand {\printdataprocessline}{}

\newcommand {\printdata}[2]{% #1 = file name, #2 string to test
  \openin\datastream=#1\relax
% the string key will be trimmed of its leading and trailing spaces
  \edef\printdatakey
  {\expandafter\xintZapSpaces\expandafter{\detokenize{#2}}}%
%
  \edef\printdatatestkey
      {\unexpanded{\def\printdatatestkey ##1}\printdatakey 
       \unexpanded{##2\relax ##3\par {\ifx\relax##2\relax\else ##3\par\fi}}}
%
  \printdatatestkey % sets up \printdatatestkey macro to seek the key.
% [added a ; to avoid false positives if for example the seeked key is BB
%  and the actual one is B.]
  \edef\printdataprocessline ##1;##2\relax
     {\noexpand\printdatatestkey ##1;\printdatakey\relax 
      \printdatakey: \noexpand\xintZapSpaces {##2}\noexpand\par }%
%
  \xintloop
    \read\datastream to \onedataline
% detokenize the line for safe handling. 
% \odef expands once the argument, this is enough
    \odef\onedataline{\detokenize\expandafter{\onedataline}}%
  \unless\ifeof\datastream
    \expandafter\printdataprocessline\onedataline\relax
% j'aurais dû faire directement
%  \expandafter\printdataprocessline\detokenize\expandafter{\onedataline}\relax
  \repeat
  \closein\datastream
}

\begin{document}\thispagestyle{empty}

Testing A:

\printdata{\jobname.dat}{ A }

\medskip

Testing B:

\printdata{\jobname.dat}{ B}

\medskip

% sans le ; faux positif sur Berlin
Testing BB:

\printdata{\jobname.dat}{BB}

\medskip

Testing D:

\printdata{\jobname.dat}{ D }

\end{document}

密钥匹配

Answer

更新：已添加强制 xinttools 方法

有两个问题。第一个问题是\isinfrom 包xifthen没有展开它的第二个参数，这里是\dbline。第二个问题是\isin 使用的 LaTeX 内核\in@无法处理\par标记；但 TeX 总是会\par在通过的文件输入末尾附加一个标记\read，除非 \endlinechar 设置为 -1。

第一个问题可以通过定义一个\isinxp扩展其第二个参数的包装器来解决。第二个问题（假设\endlinechar不是 -1）通过在读取行之后和测试之前测试文件末尾来解决。

\documentclass[12pt, a4paper]{article}
\usepackage{filecontents}

\begin{filecontents*}{cities.txt}
A;London
B;Berlin
C;Paris
\end{filecontents*}

\usepackage{xstring}
\usepackage{xifthen}

% star form as anyhow \isin is declared short, and furthermore
% uses internally \in@ from the LaTeX kernel which is short
\newcommand*{\isinxp}[2]{\expandafter\isinxpp\expandafter{#2}{#1}}
\newcommand*{\isinxpp}[2]{\isin {#2}{#1}}

\begin{document}\thispagestyle{empty}

\newread\dbcities
\openin\dbcities=cities.txt

We start here:

\loop
    \read\dbcities to \dbline 
% (testing)   \texttt{\meaning\dbline}
\unless\ifeof\dbcities
    \ifthenelse{\isinxp{A}{\dbline}}
    {\StrCut{\dbline}{;}{\colA}{\colB}
    \colA: \colB \\}
    {}
\repeat

\closein\dbcities

\end{document}

字符串比较 ifthen

强制性新工具方法：

（我已经修正了键匹配，因为搜索BB会返回带有B键的数据行的误报。请注意，包含BB键的数据行在查找时返回正值B是预期的事情，正如 OP 所使用的那样\isin。）

\documentclass[12pt, a4paper]{article}
\usepackage{filecontents}
\begin{filecontents*}{\jobname.dat}
A;London
  B;   Berlin
BB; Hamburg
 C  ;  Paris
 A ;  London again
D;Roma
\end{filecontents*}

\usepackage{xinttools}

\newread\datastream

% to issue warnings if command names already in use, then one knows one
% has to change them (depens on loaded packages)
\newcommand {\onedataline}{}
\newcommand {\printdatakey}{}
\newcommand {\printdatatestkey}{}
\newcommand {\printdataprocessline}{}

\newcommand {\printdata}[2]{% #1 = file name, #2 string to test
  \openin\datastream=#1\relax
% the string key will be trimmed of its leading and trailing spaces
  \edef\printdatakey
  {\expandafter\xintZapSpaces\expandafter{\detokenize{#2}}}%
%
  \edef\printdatatestkey
      {\unexpanded{\def\printdatatestkey ##1}\printdatakey 
       \unexpanded{##2\relax ##3\par {\ifx\relax##2\relax\else ##3\par\fi}}}
%
  \printdatatestkey % sets up \printdatatestkey macro to seek the key.
% [added a ; to avoid false positives if for example the seeked key is BB
%  and the actual one is B.]
  \edef\printdataprocessline ##1;##2\relax
     {\noexpand\printdatatestkey ##1;\printdatakey\relax 
      \printdatakey: \noexpand\xintZapSpaces {##2}\noexpand\par }%
%
  \xintloop
    \read\datastream to \onedataline
% detokenize the line for safe handling. 
% \odef expands once the argument, this is enough
    \odef\onedataline{\detokenize\expandafter{\onedataline}}%
  \unless\ifeof\datastream
    \expandafter\printdataprocessline\onedataline\relax
% j'aurais dû faire directement
%  \expandafter\printdataprocessline\detokenize\expandafter{\onedataline}\relax
  \repeat
  \closein\datastream
}

\begin{document}\thispagestyle{empty}

Testing A:

\printdata{\jobname.dat}{ A }

\medskip

Testing B:

\printdata{\jobname.dat}{ B}

\medskip

% sans le ; faux positif sur Berlin
Testing BB:

\printdata{\jobname.dat}{BB}

\medskip

Testing D:

\printdata{\jobname.dat}{ D }

\end{document}

密钥匹配

Question 2

LaTeX3 的实现。

\begin{filecontents*}{\jobname.dat}
A;London
B;Berlin
C;Paris
\end{filecontents*}

\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn
\NewDocumentCommand{\printdata}{ mm }
 {% #1 is the file name, #2 is the key to test
  \christof_printdata:nn { #1 } { #2 }
 }

\ior_new:N \g_christof_data_stream

\cs_new_protected:Npn \christof_printdata:nn #1 #2
 {% do a mapping on file #1
  \ior_open:Nn \g_christof_data_stream { #1 }
  \ior_map_inline:Nn \g_christof_data_stream
   {% every entry is of the form "key;value", ##1 stands for the whole line
    \__christof_process_line:nww { #2 } ##1 \q_stop
   }
 }

\cs_new_protected:Npn \__christof_process_line:nww #1 #2 ; #3 \q_stop
 {% #1 is the key to test, #2 is the key, #3 is the value
  \tl_if_in:nnT { #2 } { #1 }
   {
    \tl_trim_spaces:n { #2 }: ~ \tl_trim_spaces:n { #3 } \par
   }
 }
\ExplSyntaxOff

\begin{document}

Testing A:

\printdata{\jobname.dat}{A}

\medskip

Testing B:

\printdata{\jobname.dat}{B}

\end{document}

在此处输入图片描述

以下是展示真实需求后的实现。

\begin{filecontents*}{\jobname.dat}
§
§1§~{Mich respektvoll verneigend vor den Sugatas, vor dem Körper der Wahrheit, den sie besitzen, sowie vor  ihren Kindern und ebenso vor allen, die der Verehrung wert  sind, will ich die Ausübung der Disziplin der  Sugata-Kinder entsprechend den Schriften in  zusammengefasster Form darlegen.}
§
§2§~{Etwas, das es zuvor noch nicht gegeben hat, habe auch ich hier nicht zu sagen; und ich besitze nicht die Kunstfertigkeit in der Komposition von Schriften: Deshalb habe ich auch keine Absicht, anderen zu nutzen; vielmehr schreibe ich dieses, um meinen eigenen Geist daran zu gewöhnen.}
§
§3§~{Aufgrund der Gewöhnung an das Heilsame mag die Kraft meines Vertrauens durch diese Kontemplationen zeitweilig anwachsen; und wenn andere, die mir in ihren Veranlagungen ähnlich sind, diese sehen, so mag es auch für sie von Bedeutung sein.}
§
\end{filecontents*}

\documentclass{article}
\usepackage{fontspec}

\usepackage{polyglossia} % the multilingual support package
\setdefaultlanguage[spelling=new, babelshorthands=true]{german}

\usepackage{xparse}

\usepackage{xparse}

\ExplSyntaxOn
% generic command
\NewDocumentCommand{\printdata}{ mm }
 {% #1 is the file name, #2 is the key to test
  \christof_printdata:nn { #1 } { #2 }
 }
% with fixed file name
\NewDocumentCommand{\myprintverse}{ m }
 {
  \printdata { \jobname.dat } { #1 } % <--- Fix the file name
 }

\ior_new:N \g_christof_data_stream
\seq_new:N \l__christof_entry_seq

\cs_new_protected:Npn \christof_printdata:nn #1 #2
 {
  \ior_open:Nn \g_christof_data_stream { #1 }
  \ior_map_inline:Nn \g_christof_data_stream
   {
    \tl_if_in:nnT { ##1 } { #2 }
     {
      \__christof_process_line:ww ##1 \q_stop
     }
   }
 }

\group_begin:
\char_set_catcode_active:N \^^A
\char_set_lccode:nn { `\^^A } { `\~ }
\tl_to_lowercase:n 
 {
  \group_end:
  \cs_new_protected:Npn \__christof_process_line:ww §#1§ ^^A #2 \q_stop
 }
 {% #1 is the key, #2 is the value
  (#1) \nobreakspace \tl_trim_spaces:n { #2 }
 }
\ExplSyntaxOff

\begin{document}

Each line of data printed in a seperate paragraph:
\medskip

\myprintverse{§1§}

\myprintverse{§2§}

\myprintverse{§3§}

\bigskip

Two lines in one paragraph results in proper space between them

\medskip

\myprintverse{§1§} \myprintverse{§2§}

\myprintverse{§3§}\footnote{This is also a problem if I want to add a footnote.}

\end{document}

由于是一个特殊字符，因此这个\tl_to_lowercase:n技巧是必要的。~

在此处输入图片描述

Answer

LaTeX3 的实现。

\begin{filecontents*}{\jobname.dat}
A;London
B;Berlin
C;Paris
\end{filecontents*}

\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn
\NewDocumentCommand{\printdata}{ mm }
 {% #1 is the file name, #2 is the key to test
  \christof_printdata:nn { #1 } { #2 }
 }

\ior_new:N \g_christof_data_stream

\cs_new_protected:Npn \christof_printdata:nn #1 #2
 {% do a mapping on file #1
  \ior_open:Nn \g_christof_data_stream { #1 }
  \ior_map_inline:Nn \g_christof_data_stream
   {% every entry is of the form "key;value", ##1 stands for the whole line
    \__christof_process_line:nww { #2 } ##1 \q_stop
   }
 }

\cs_new_protected:Npn \__christof_process_line:nww #1 #2 ; #3 \q_stop
 {% #1 is the key to test, #2 is the key, #3 is the value
  \tl_if_in:nnT { #2 } { #1 }
   {
    \tl_trim_spaces:n { #2 }: ~ \tl_trim_spaces:n { #3 } \par
   }
 }
\ExplSyntaxOff

\begin{document}

Testing A:

\printdata{\jobname.dat}{A}

\medskip

Testing B:

\printdata{\jobname.dat}{B}

\end{document}

在此处输入图片描述

以下是展示真实需求后的实现。

\begin{filecontents*}{\jobname.dat}
§
§1§~{Mich respektvoll verneigend vor den Sugatas, vor dem Körper der Wahrheit, den sie besitzen, sowie vor  ihren Kindern und ebenso vor allen, die der Verehrung wert  sind, will ich die Ausübung der Disziplin der  Sugata-Kinder entsprechend den Schriften in  zusammengefasster Form darlegen.}
§
§2§~{Etwas, das es zuvor noch nicht gegeben hat, habe auch ich hier nicht zu sagen; und ich besitze nicht die Kunstfertigkeit in der Komposition von Schriften: Deshalb habe ich auch keine Absicht, anderen zu nutzen; vielmehr schreibe ich dieses, um meinen eigenen Geist daran zu gewöhnen.}
§
§3§~{Aufgrund der Gewöhnung an das Heilsame mag die Kraft meines Vertrauens durch diese Kontemplationen zeitweilig anwachsen; und wenn andere, die mir in ihren Veranlagungen ähnlich sind, diese sehen, so mag es auch für sie von Bedeutung sein.}
§
\end{filecontents*}

\documentclass{article}
\usepackage{fontspec}

\usepackage{polyglossia} % the multilingual support package
\setdefaultlanguage[spelling=new, babelshorthands=true]{german}

\usepackage{xparse}

\usepackage{xparse}

\ExplSyntaxOn
% generic command
\NewDocumentCommand{\printdata}{ mm }
 {% #1 is the file name, #2 is the key to test
  \christof_printdata:nn { #1 } { #2 }
 }
% with fixed file name
\NewDocumentCommand{\myprintverse}{ m }
 {
  \printdata { \jobname.dat } { #1 } % <--- Fix the file name
 }

\ior_new:N \g_christof_data_stream
\seq_new:N \l__christof_entry_seq

\cs_new_protected:Npn \christof_printdata:nn #1 #2
 {
  \ior_open:Nn \g_christof_data_stream { #1 }
  \ior_map_inline:Nn \g_christof_data_stream
   {
    \tl_if_in:nnT { ##1 } { #2 }
     {
      \__christof_process_line:ww ##1 \q_stop
     }
   }
 }

\group_begin:
\char_set_catcode_active:N \^^A
\char_set_lccode:nn { `\^^A } { `\~ }
\tl_to_lowercase:n 
 {
  \group_end:
  \cs_new_protected:Npn \__christof_process_line:ww §#1§ ^^A #2 \q_stop
 }
 {% #1 is the key, #2 is the value
  (#1) \nobreakspace \tl_trim_spaces:n { #2 }
 }
\ExplSyntaxOff

\begin{document}

Each line of data printed in a seperate paragraph:
\medskip

\myprintverse{§1§}

\myprintverse{§2§}

\myprintverse{§3§}

\bigskip

Two lines in one paragraph results in proper space between them

\medskip

\myprintverse{§1§} \myprintverse{§2§}

\myprintverse{§3§}\footnote{This is also a problem if I want to add a footnote.}

\end{document}

由于是一个特殊字符，因此这个\tl_to_lowercase:n技巧是必要的。~

在此处输入图片描述

\ifthenelse 中的字符串比较

答案1

答案2

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