Automatic line breaking of long lines of text?

Question

Here, it is just a example. I have a line:

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaa

Now, I want to let LaTeX automatically wrap the line according to the width of the text block/margins.

Answer 1

You are probably looking for something like the seqsplit package.

\documentclass[11pt]{article}
\usepackage{seqsplit}

\begin{document}
  \seqsplit{aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa}
\end{document}

---

Update:

For lines with spaces the \seqsplit command can of course be used several times.

\documentclass[11pt]{article}
\usepackage{seqsplit}

\begin{document}
  \seqsplit{aaaaaaaaaaaaaaaaaaaaaaaa} \seqsplit{aaaaaaaaaaaaaaaaaaaaaaaaaaaaa} \seqsplit{aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa} \seqsplit{aaaaaaaaaaaaaaa}
\end{document}

Answer 2

If a word is too long and it does not have a hyphenation pattern, the TeX engine does not know where to insert a break. You can force it by adding a minuscule amount of glue in-between the letters. TeX will then be able to insert a break. How much glue? As it happens even 1sp which is the smallest unit can do the trick (there are 65 536 scaled points in a point, which is less than the wavelength of visible light). All we need is a scanner to scan through the letters. Here is a minimal:

\documentclass{article}
\usepackage{lipsum}
\begin{document}
\parindent0pt
\makeatletter
\def\scanfunction#1{#1}
\let\tempa\@empty
\def\scan@letters#1#2{%
   \g@addto@macro{\tempa}{#1\hskip 0pt plus 1sp minus 1sp}%
   \ifx#2\@empty
     \else 
       \expandafter\scan@letters
   \fi
#2}

\def\scan#1{%
  \scan@letters #1\@empty
}
\scan{aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa}
\tempa

\lipsum[1]
\end{document}

Edit: egreg at chat brought to my attention that even hskip 0pt will also work.

Answer 3

You can adapt the solution to Option to break urls with carriage-return symbol? which used the hyphenat pacakge to add a breakable character after each character.

Here is the output for various widths. The last paragraph width was chosen to ensure that the hyphen was not added if the break occurred at a space.

\documentclass[border=5pt]{standalone}
\usepackage{hyphenat}
\usepackage{xstring}
\usepackage{forloop}

\newsavebox\MyBreakChar%
\sbox\MyBreakChar{\hyp}% char to display the break after non char
\newsavebox\MySpaceBreakChar%
\sbox\MySpaceBreakChar{}% char to display the break after space
\makeatletter%
\newcommand*{\BreakableChar}[1][\MyBreakChar]{%
  \leavevmode%
  \prw@zbreak%
  \discretionary{\usebox#1}{}{}%
  \prw@zbreak%
}%

\newcounter{index}%
\newcommand{\AddBreakableChars}[1]{%
  \StrLen{#1 }[\stringLength]%
  \forloop[1]{index}{1}{\value{index}<\stringLength}{%
    \StrChar{#1}{\value{index}}[\currentLetter]%
    \IfStrEq{\currentLetter}{ }
        {\currentLetter\BreakableChar[\MySpaceBreakChar]}%
        {\currentLetter\BreakableChar[\MyBreakChar]}%
  }%
}%

\newcommand*{\MyLongString}{aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa baaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa caaaaaaaaaaaaaaaaaa}%

\begin{document}
\parbox{4cm}{\AddBreakableChars{\MyLongString}}

\bigskip
\parbox{7cm}{\AddBreakableChars{\MyLongString}}

\bigskip
\parbox{9.1cm}{\AddBreakableChars{\MyLongString}}
\end{document}