[Tex/LaTex] How to set italics and bold shortcuts like *bold* or _italic_

boldformattingitalicsyntax

I remember seeing a possible solution here, but can't find it.
Is there any way to simplify bold and italics so that instead of \textbf{bold text} and \textit{italics text} I use simple marks like (such as in Word) bold text

*bold text* 

and italics

_italics_

for the whole document?

Best Answer

For the underscore, the following works:

\documentclass{article}

\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{lmodern}
\usepackage[ngerman]{babel}

\catcode`\_=\active
\protected\def_{\begingroup\itshape\aftergroup\/\let_\endgroup}

\begin{document}

Hello \textit{World!} How are you?

Hello _World!_ How are _you?

I'm fine._ And you?

_I'm fine, too.

Glad to hear that._

\end{document}

However, it is a bit crazy and unstable. If you want to use it only for short texts (not spanning multiple paragraphs), the following would be better. (It doesn't work in the above example, since there we span multiple pagraphs. In real, it will throw an error if you put odd number of _ in one paragraph.)

\catcode`\_=\active
\protected\def_#1_{\textit{#1}}

You can use the same ideas for the star. The problem is, that \section*{Text} will suddenly stop working. Variant 1:

\catcode`\*=\active
\protected\def*{\begingroup\bfseries\let*\endgroup}

Variant 2:

\catcode`\*=\active
\protected\def*#1*{\textbf{#1}}

If you don't use math at all, just use ^ instead of * and it should be ok.


How does it work: The primitive macro \catcode makes _ \active so that we can define it as any other command.

In Variant 1, we define it to (1) start a group (2) start italic text (3) add italic correction to the end of the italic text (4) make the one next _ end the group we started. By the end of the group, the re-definition of _ is forgotten so another _ will again start an italic text.

The Variant 2 is even simpler: When _ is found, a second _ is looked for, end everything inbetween is put into \textit.

The \protected directive makes sure that _ is written as _ in the auxiliary files, which is necessary for it to behave correctly.

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