truncate text from left to right

Question

I simply need to truncate a text string, which is just a sequence of characters without whitespace, therefore the linebreak won't work. I just need to decide the length of the string in centimeter, the rest should be cut.

I found the package trimclip which could do it, but I need a way to do it without the usage of this package (I can still use existing, common packages)

I hope there is another possibility. I found a very nice way to do it if you want to cut the string from the right side. But I need it from the other side.

I will give a short example how my document should look like:

\documentclass{article}
\newcommand\magicCommand[1]{
      ...
}
\begin{document}

\begin{table}[htb]
\begin{center}
\begin{tabular}{l}

\begin{tabular}{|ll|}
\hline

\parbox{50mm}{ \magicCommand{3cm}{veryLongStringWhichIsGoingToLookUglyInMyDocument}} & \parbox{40mm}{ abc }\\

\hline
\end{tabular}

\end{tabular}
\end{center}
\end{table}

\end{document}

The text for the example above should look in the document like:

veryLongStri

\EDIT

Sorry for this long edit, but I am pretty confused. The truncate seems to be buggy somehow (dependent from the string) and as you can see I made some other tests. There are some solutions which seem to work properly. I don't know what problem I had before because some versions only worked outside the tabular environments.

test.tex

\documentclass[10pt]{article}
\usepackage{a4,graphicx}
\usepackage[breakwords]{truncate}

\setlength{\oddsidemargin}{0cm}
\setlength{\evensidemargin}{0cm}
\setlength{\topmargin}{-2.0cm}
\setlength{\textwidth}{16cm}
\setlength{\textheight}{28.65cm}
\setlength{\headsep}{1.0cm}
\setlength{\parindent}{1.0cm}
\newcommand{\singlespace}{\renewcommand{\baselinestretch}{1.0}\small\normalsize}\newcommand{\doublespace}{\renewcommand{\baselinestretch}{1.5}\small\normalsize}
\renewcommand{\floatpagefraction}{0.95}
\renewcommand{\textfraction}{0.05}
\renewcommand{\topfraction}{0.95}
\renewcommand{\bottomfraction}{0.95}

%===new===

\newlength{\stringlen}
\newbox\stringbox
\newcommand{\clipstring}[2][6cm]{%
  \setlength\stringlen{#1}%
  \sbox\stringbox{}%
  \doclipstring#2\doclipstring
}

\makeatletter
\newcommand{\doclipstring}[1]{%
  \ifx#1\doclipstring
    \expandafter\@firstoftwo
  \else
    \expandafter\@secondoftwo
  \fi
  {\unhbox\stringbox}%
  {\check@cliplength{#1}}%
}
\def\check@cliplength#1{%
  \sbox\stringbox{\unhcopy\stringbox #1}
  \ifdim\wd\stringbox>\stringlen
    \expandafter\@firstoftwo
  \else
    \expandafter\@secondoftwo
  \fi
  {\unhbox\stringbox\removetrailing}%
  {\doclipstring}%
}
\def\removetrailing#1\doclipstring{}
\makeatother

%=========

\usepackage{xcolor}
\newcommand\tleft[3][white]{%
  \setbox0=\hbox{\x}%
  \makebox[#2][l]{%
    \ooalign{\mbox{#3}\cr\kern#2\textcolor{#1}{%
      \rule[-\dp0]{\wd0}{\dimexpr\dp0+\ht0}}}}%
}

%=========

\makeatletter
\newcommand\jw[2][2cm]{%
  \leavevmode
  \begingroup
    \setbox0=\hbox{#2}%
    \setbox0=\hbox{%
      \pdfsave
      \pdfliteral{%
        0 \dim@in@bp{-\dp0 } \dim@in@bp{#1} \dim@in@bp{\ht0 + \dp0 }
        re W n}%
        \rlap{\box0 }%
      \pdfrestore
      \hskip#1 %
    }%
    \box0 %
  \endgroup
}
\newcommand\dim@in@bp[1]{%
  \strip@pt\dimexpr(#1) * 800/803\relax
}
\makeatother

%=========


\begin{document}

\pagestyle{empty}
\begin{table}[htb]
\begin{center}
\begin{tabular}{l}
\begin{tabular}{|ll|}
\hline
 \parbox{60mm}{ thoseAreTheVeryLongStringsWeWantToCutOtherwiseTheTableLooksLikeCrap\_bad }& \parbox{80mm}{ 0.031 }\\

 \parbox{60mm}{ \truncate{6cm}{qwfioqoiwefjiuwgwejfmqefiuhSiqwdMwqkdwqmkMqdwmDWmdwklqwdmlDMlkqwlkdMDLWQd} }& \parbox{80mm}{ 2.047 }\\
 \parbox{60mm}{ \truncate{6cm}{qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq\_qqqq} }& \parbox{80mm}{ 2.047 }\\
 \parbox{60mm}{ \truncate{6cm}{aaaaaaaa\_qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq\_qqqq} }& \parbox{80mm}{ 2.047 }\\
 \parbox{60mm}{ \truncate{6cm}{truncate\_qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq\_qqqq} }& \parbox{80mm}{ 2.047 }\\
 \parbox{60mm}{ \truncate{6cm}{thoseAreTheVeryLongStringsWeWantToCutOtherwiseTheTableLooksLikeCrap\_good} }& \parbox{80mm}{ 1.023 }\\

 \parbox{60mm}{ \clipstring{clipstring\_thoseAreTheVeryLongStringsWeWantToCutOtherwiseTheTableLooksLikeCrap} }& \parbox{80mm}{ 1.023 }\\

 \parbox{60mm}{ \tleft{6cm}{tleft\_thoseAreTheVeryLongStringsWeWantToCutOtherwiseTheTableLooksLikeCrap} }& \parbox{80mm}{ 1.023 }\\

 \parbox{60mm}{ \jw[6cm]{jw\_thoseAreTheVeryLongStringsWeWantToCutOtherwiseTheTableLooksLikeCrap} }& \parbox{80mm}{ 1.023 }\\
 \parbox{60mm}{ \jw[6cm]{jw\_qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq\_qqqq} }& \parbox{80mm}{ 1.023 }\\

\hline
\end{tabular}
\end{tabular}
\end{center}
\end{table}

\end{document}

testoutput

pdflatex.log

This is pdfTeXk, Version 3.141592-1.40.3 (Web2C 7.5.6)
 %&-line parsing enabled.
entering extended mode
(./test.tex
LaTeX2e <2005/12/01>
Babel <v3.8h> and hyphenation patterns for english, usenglishmax, dumylang, noh
yphenation, arabic, basque, bulgarian, coptic, welsh, czech, slovak, german, ng
erman, danish, esperanto, spanish, catalan, galician, estonian, farsi, finnish,
 french, greek, monogreek, ancientgreek, croatian, hungarian, interlingua, ibyc
us, indonesian, icelandic, italian, latin, mongolian, dutch, norsk, polish, por
tuguese, pinyin, romanian, russian, slovenian, uppersorbian, serbian, swedish, 
turkish, ukenglish, ukrainian, loaded.
(/usr/share/texmf/tex/latex/base/article.cls
Document Class: article 2005/09/16 v1.4f Standard LaTeX document class
(/usr/share/texmf/tex/latex/base/size10.clo))
(/usr/share/texmf/tex/latex/ntgclass/a4.sty)
(/usr/share/texmf/tex/latex/graphics/graphicx.sty
(/usr/share/texmf/tex/latex/graphics/keyval.sty)
(/usr/share/texmf/tex/latex/graphics/graphics.sty
(/usr/share/texmf/tex/latex/graphics/trig.sty)
(/usr/share/texmf/tex/latex/config/graphics.cfg)
(/usr/share/texmf/tex/latex/pdftex-def/pdftex.def)))
(/usr/share/texmf/tex/latex/ltxmisc/truncate.sty)
(/usr/share/texmf/tex/latex/xcolor/xcolor.sty
(/usr/share/texmf/tex/latex/config/color.cfg)) (./test.aux)
Overfull \hbox (194.49529pt too wide) in paragraph at lines 96--96
[]\OT1/cmr/m/n/10 thoseAreTheVeryLongStringsWeWantToCutOtherwiseTheTableLooksLi
keCrap[]bad 

Overfull \hbox (207.60631pt too wide) detected at line 99
\OT1/cmr/m/n/10 qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq
qqqq[]qqqq 

Overfull \hbox (251.20644pt too wide) detected at line 100
\OT1/cmr/m/n/10 aaaaaaaa[]qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq
qqqqqqqqqqqqqq[]qqqq 

Overfull \hbox (3.02272pt too wide) in paragraph at lines 104--104
[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][
]\OT1/cmr/m/n/10 c[]l[]i[]p[]s[]t[]r[]i[]n[]g[][][]t[]h[]o[]s[]e[]A[]r[]e[]T[]h
[]e[]V[]e[]r[]y[]L[]o[]n[]g[]S[]t[]r[]i[]n[]g[]s[] 
! Undefined control sequence.
\\tleft [#1]#2#3->\setbox 0=\hbox {\x 
                                      }\makebox [#2][l]{\ooalign {\mbox {#3}...
l.106 ...antToCutOtherwiseTheTableLooksLikeCrap} }
                                                  & \parbox{80mm}{ 1.023 }\\
? [1{/usr/share/texmf/fonts/map/pdftex/updmap/pdftex.map}] (./test.aux) )</usr/sh
are/texmf/fonts/type1/bluesky/cm/cmr10.pfb>
Output written on test.pdf (1 page, 12123 bytes).
Transcript written on test.log.

Answer 1

Use the truncate package

\documentclass{article}
\usepackage[breakwords]{truncate}
\begin{document}
\truncate{3cm}{This text has been~truncated}
\end{document}

The package uses a clever stategy based on hyphenation. But a word of warning, if you just insert long nonsense letter sequences it may have a problem finding a breakpoint. Use sensible text and works very well. Do read the docs. Use texdoc truncate from the command line, is the quickest way.

Answer 2

When doing most box manipulations, you can refer to \width that contains the box's natural width.

\documentclass{article}
\usepackage{trimclip}

\newcommand\clipstring[2][3cm]{%
  \clipbox{0pt 0pt {\dimexpr\width-#1\relax} 0pt}{#2}%
}

\begin{document}

\clipstring{veryLongStringWhichIsGoingToLookUglyInMyDocument} is
not too long any more

\makebox[3cm]{\hrulefill} is not too long any more

\end{document}

I added an optional argument to \clipstring, so you can adjust the length at run time with, say, \clipstring[2cm]{...}.

You may want a macro that clips a string in typewriter type, specifying the number of characters to keep:

\documentclass{article}
\usepackage{trimclip}

\newcommand\clipstring[2][3cm]{%
  \clipbox{0pt 0pt {\dimexpr\width-#1\relax} 0pt}{#2}%
}
\newcommand\clipttstring[2][10]{%
  \texttt{\clipbox{0pt 0pt {\dimexpr\width-(#1em)/2\relax} 0pt}{#2}}%
}

\begin{document}

\clipstring{veryLongStringWhichIsGoingToLookUglyInMyDocument} is
not too long any more

\makebox[3cm]{\hrulefill} is not too long any more % check

\clipttstring{veryLongStringWhichIsGoingToLookUglyInMyDocument} is
not too long any more

\texttt{0123456789} is not too long any more % check

\end{document}

The default is 10, use \clipttstring[6]{...} to keep just six characters.

---

Here is, instead, a macro that will stop print characters when the fixed length is exceeded.

\documentclass{article}

\newlength{\stringlen}
\newbox\stringbox
\newcommand{\clipstring}[2][3cm]{%
  \setlength\stringlen{#1}%
  \sbox\stringbox{}%
  \doclipstring#2\doclipstring
}

\makeatletter
\newcommand{\doclipstring}[1]{%
  \ifx#1\doclipstring
    \expandafter\@firstoftwo
  \else
    \expandafter\@secondoftwo
  \fi
  {\unhbox\stringbox}%
  {\check@cliplength{#1}}%
}
\def\check@cliplength#1{%
  \sbox\stringbox{\unhcopy\stringbox #1}
  \ifdim\wd\stringbox>\stringlen
    \expandafter\@firstoftwo
  \else
    \expandafter\@secondoftwo
  \fi
  {\unhbox\stringbox\removetrailing}%
  {\doclipstring}%
}
\def\removetrailing#1\doclipstring{}
\makeatother

\begin{document}

\clipstring{veryLongStringWhichIsGoingToLookUglyInMyDocument} is
not too long any more

\makebox[3cm]{\hrulefill} is not too long any more % check

\clipstring{shrt} is short

\end{document}

Limitations: the argument must be a string of simple ASCII characters; no spaces, though, and no accented letters.

---

A similar solution, but counting characters to keep (ten by default).

\documentclass{article}
\makeatletter
\newcommand\stringclip[2][10]{%
  \@tempcnta=#1\relax
  \@tempcntb=\z@
  \toks@={}%
  \do@stringclip#2\do@stringclip
}
\def\do@stringclip#1{%
  \ifx#1\do@stringclip
    \the\toks@\expandafter\@gobble
  \else
    \advance\@tempcntb\@ne
  \expandafter\@firstofone
  \fi
  {\check@one@more{#1}}%
}
\def\check@one@more#1{%
  \ifnum\@tempcntb=\@tempcnta
    \the\toks@ #1%
    \expandafter\@firstoftwo
  \else
    \toks@=\expandafter{\the\toks@ #1}%
    \expandafter\@secondoftwo
  \fi
  {\gobble@toend}%
  {\do@stringclip}%
}
\def\gobble@toend#1\do@stringclip{}
\makeatother

\begin{document}

\stringclip{01234567890123456789}

\stringclip[5]{01234567890123456789}

\stringclip{012345}

\end{document}

Answer 3

A solution using driver-level box clipping accessed via expl3 (interface as egreg's version):

\documentclass{article}
\usepackage{expl3,xparse}
\ExplSyntaxOn
\NewDocumentCommand \clipstring { O { 2cm } m }
  {
    \erp_clip:nn {#2} {#1}
  }
\box_new:N \l__erp_box
\cs_new_protected:Npn \erp_clip:nn #1#2
  {
    \leavevmode
    \hbox_set:Nn \l__erp_box {#1}
    \box_set_wd:Nn \l__erp_box {#2}
    \box_clip:N \l__erp_box
    \box_use:N \l__erp_box
  }
\ExplSyntaxOff

\begin{document}

\clipstring[3cm]{veryLongStringWhichIsGoingToLookUglyInMyDocument} is
not too long any more

\makebox[3cm]{\hrulefill} is not too long any more % check

\end{document}

If absolutely no packages are allowed, we can do the same thing by recoding the low-level clipping 'by hand'. This is tied to one driver, but that may be acceptable. For example, using pdfTeX or LuaTeX for direct PDF production, the above 'written out' is

\documentclass{article}
\makeatletter
\newcommand\clipstring[2][2cm]{%
  \leavevmode
  \begingroup
    \setbox0=\hbox{#2}%
    \setbox0=\hbox{%
      \pdfsave
      \pdfliteral{%
        0 \dim@in@bp{-\dp0 } \dim@in@bp{#1} \dim@in@bp{\ht0 + \dp0 }
        re W n}%
        \rlap{\box0 }%
      \pdfrestore
      \hskip#1 %
    }%
    \box0 %
  \endgroup
}
\newcommand\dim@in@bp[1]{%
  \strip@pt\dimexpr(#1) * 800/803\relax
}
\makeatother

\begin{document}
\clipstring[2.95cm]{veryLongStringWhichIsGoingToLookUglyInMyDocument} is
not too long any more

\makebox[2.95cm]{\hrulefill} is not too long any more % check

\end{document}

(I've made a few minor changes as I can hardcode some stuff in this case that I can't when writing the expl3 driver code!)

Answer 4

This uses xcolor instead of trimclip. As egreg correctly points out, my original answer will not work on a colored background. So I have EDITED it to add an optional argument, where the background color can be specified (default white).

EDITED to replace local variable \x inside the \tleft definition with (oops!) #3.

\documentclass{article}
\usepackage{xcolor}
\newcommand\tleft[3][white]{%
  \setbox0=\hbox{#3}%
  \makebox[#2][l]{%
    \ooalign{\mbox{#3}\cr\kern#2\textcolor{#1}{%
      \rule[-\dp0]{\wd0}{\dimexpr\dp0+\ht0}}}}%
}
\begin{document}
\def\x{This is my very long string}
\x

\rule{1.4cm}{2pt}

\tleft{1.4cm}{\x}NEXT
\end{document}