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I very much {like, use} the kmacro-*-counter family of commands. However I sometimes find myself needing to generate alphabetic sequences (e.g., A, B, C, ...) instead of integer sequences (e.g., 1, 2, 3 ...). I can sorta see how to do this in 2 passes using query-replace-regexp and something like make-string, but that means 1st generating the integer sequence and then replacing it.

Is there an easier way? Particularly, is there some {command, function, package} that will support a usecase like

  1. M-x foo-set-alpha-counter A
  2. (loop) M-x foo-insert-counter

?

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    I don't use macros, but you may find it helpful to know that Emacs uses numbers for letters such as (char-to-string 65) is the capital letter "A". And, this increments sequentially, e.g., (char-to-string 66) is the capital letter "B". Lowercase letters begin at 97; e.g., (char-to-string 97) is the lowercase letter "a"; and, it continues sequentially; e.g., (char-to-string 98) is the lowercase letter "b". To check the number, you can do the reverse -- (string-to-char "A") returns the number 65.
    – lawlist
    Aug 29, 2019 at 23:42
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    Coding is according to the ASCII standard. See 'man ascii'
    – Heikki
    Aug 30, 2019 at 5:26

1 Answer 1

Reset to default
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You can use the function kmacro-set-format, normally bound to C-x C-k C-f, to change the (printf-style) format used to insert the macro counter. You can set it to %c to treat the value of the macro counter as an ASCII code.

For example to produce a letter sequence like ABCDEF: set the format to %c, start the macro counter at 65 which is the ASCII code for A, then record a macro that inserts the counter and run it 6 times, say:

C-x C-k C-f %c RET C-u 65 <f3> <f3> C-6 <f4>

As a neat extra touch, if you change the format inside the keyboard macro, the change only affects that particular macro. So, after running the above, the format will still be %c for the next keyboard macro, but if instead you do:

C-u 65 <f3> C-x C-k C-f %c RET <f3> C-6 <f4>

then the %c is local to that macro.

%d to go back to numbers.

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    Thanks! Works great, plus this validates my otherwise-bizarre notion that my laminated ASCII-code card from 1982 would eventually prove handy :-)
    – TomRoche
    Sep 1, 2019 at 17:02
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    @TomRoche :) If you ever loose that laminated card and you use GNU/Linux, you can run man ascii to see a nice chart (M-x man or M-x woman from within Emacs).
    – Omar
    Sep 1, 2019 at 17:57
  • @Omar Awesome tip. Is there any way to be able to just insert the char and have emacs convert it?
    – mcp
    Sep 18, 2020 at 22:48
  • Not as part of that key sequence; but you can certainly ask Emacs what the number is beforehand, by evaluating the read syntax for a character. E.g. M-: ?A tells you 65 (or vice versa, evaluating 65 tells you ?A).
    – phils
    Sep 23, 2020 at 0:42
  • If it helps, in elisp code you would use the read-char function to ask the user to type a character, and obtain that value.
    – phils
    Sep 23, 2020 at 0:47

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