Emacs Lisp: getting ascii value of character

Question

I'd like to translate a character in Emacs to its numeric ascii code, similar to casting char a = 'a'; int i = (int)a in c. I've tried string-to-number and a few other functions, but none seem to make Emacs read the char as a number in the end.

What's the easiest way to do this?

score 16 · Answer 1 · answered Nov 08 '13 at 19:39

16

To get the ascii-number which represents the character --as Drew said-- put a question mark before the character and evaluate that expression

?a ==> 97

Number appears in minibuffer, with C-u it's written behind expression.

Also the inverse works

(insert 97) will insert an "a" in the buffer.

BTW In some cases the character should be quoted

?\" will eval to 34

answered Nov 08 '13 at 19:39

Andreas Röhler

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Follow up question, what if I want to convert 97 into the character 'a' now? – Cameron Feb 27 '17 at 20:07
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Try for example: (insert 97)(print 97)(message "%c" 97)(eval 97) – Andreas Röhler Mar 01 '17 at 13:23

score 8 · Answer 2 · answered Nov 08 '13 at 17:28

A character is a whole number in Emacs Lisp. There is no separate character data type.

Function string-to-char is built-in, and does what you want. (string-to-char "foo") is equivalent to (aref "foo" 0), which is @abo-abo's answer --- but it is coded in C.

score 6 · Accepted Answer · answered Nov 08 '13 at 15:23

6

String is an array.

(aref "foo" 0)

answered Nov 08 '13 at 15:23

abo-abo

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Emacs Lisp: getting ascii value of character

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