I am a LaTeX guy, slowly working into the miracles of TeX.

Can anybody tell me the differences between \def, \edef, \gdef and \xdef?

Where shall I use which, what are the pros and cons? Or is it suspected to be unclean code, if I mix TeX commands in LaTeX?

Please give a short example, of how to use the command.

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    I can recommend 'Notes on Programming in TeX' written by Christian Feuersänger, which gives a lot of insights on this in a short and easy-to-read text.
    – pschulz
    Commented Feb 10, 2017 at 12:18
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    @HenriMenke thank you for your comment, that is a phantastic Q&A. But it does not cover \gdef and \xdef.
    – Jan
    Commented Feb 10, 2017 at 12:25
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    Yes, exactly! Sorry for not providing the link, i'm just so used to using texdoc, so it's a simple texdoc programming for me.
    – pschulz
    Commented Feb 10, 2017 at 12:29
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    @Jan \gdef (\xdef) is merely a shorthand for \global\def (\global\edef), so the question about these can be reduced to \def and \edef. Commented Feb 10, 2017 at 12:50
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    @HenriMenke: Thank you again for that information. Therefore, you are right, my question is a duplicate to your given Link.
    – Jan
    Commented Feb 10, 2017 at 15:47

1 Answer 1


There are no pros and cons: \def and \edef perform different tasks. With

\def<cs><parameter text>{<replacement text>}

you define <cs> to look for its arguments (if any) and to be replaced by <replacement text>, which is not interpreted in any way at definition time. With

\edef<cs><parameter text>{<replacement text>}

the replacement text is fully expanded at definition time.

For instance, if we have


a call like

\bbb \ccc

would produce


because the replacement text of \ccc is what remains after full expansion, so \edef\ccc{y\aaa} is the same as \def\ccc{yaaa}.

Note that the expansion in \edef is done at definition time, so parameter tokens like #1 and so on will be untouched.

A less silly example: if you want that \thissection expands to the value of the section counter at the time the command is defined, you have to say


because this “freezes” the value by doing the expansion at definition time. To the contrary, with \def\thissection{\thesection} the macro \thissection would print the current section number.

LaTeX has the variant \protected@edef that avoids some quirks with “robust macros”, so something like \protected@edef\cs{\textbf{a}} works whereas \edef\cs{\textbf{a}} wouldn't (there's plenty of examples on the site).

About \gdef and \xdef there's not much to say: the former is completely equivalent to \global\def and the latter to \global\edef (assuming primitive meaning of \global, of course). LaTeX has \protected@xdef.

  • Thank you @egreg. This is again a very informative and helpful answer. I still have to fiddle about \global. :-)
    – Jan
    Commented Feb 10, 2017 at 12:36
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    @Jan -- \global simply means that the definition persists when the current group closes, instead of the pre-group definition being restored. Commented Feb 10, 2017 at 15:01
  • @barbarabeeton thank you. I added an answer to the original question, as I did a search with all four \?defs and did not find an answer. Now it should be found in either way. I am personally glad, I finally learned about that TeX stuff. Next target: what is \long good for?
    – Jan
    Commented Feb 11, 2017 at 11:22
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    @Jan -- a separate question about the meaning of \long could be useful; i couldn't find any, although it's not easy to look for. i did find this: Is there a simple way to retroactively add the \long prefix to a macro's definition?, but it presupposes that someone already knows the meaning. actually, the meaning is simple: a \long macro can include a paragraph break, whereas a macro that is not \long will throw an error if it encounters \par or a blank line. Commented Feb 11, 2017 at 16:30

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