CODEWITHSUNDEEP
cmacroscharacter-encodingc-preprocessorc-strings
Rena
Rena

Reputation: 646

C: Writing a macro to build string escape sequences

I'm working with some Japanese C code that prints text in Shift-JIS. In the original code, the text is written directly in kana in string literals. In my editor that expects UTF-8, it shows up as nonsense.

In particular this code likes to use "large" versions of English letters: http://www.rikai.com/library/kanjitables/kanji_codes.sjis.shtml e.g. \x82\x60 = Ａ (a large "A", \x41 in ASCII). I thought I'd write a CPP macro to convert those from ASCII, like:

#define LARGE_LETTER(x) "\x82\x" (x+31)

But obviously, this macro doesn't quite work, and I'm not sure how to make it work, if it's even possible. Can you build string escape sequences like this?

Upvotes: 2

Views: 387

Answers (1)

Jeffery Thomas
Jeffery Thomas

Reputation: 42588

Well to start off with, why not have a lot of defines

#define LARGE_LETTER_A "\x82\x60"
#define LARGE_LETTER_B "\x82\x61"
…
#define LARGE_LETTER_Z "\x82\x7A"

Usage

char *str = "foo " LARGE_LETTER_A " baz";

Next, you can take it up a notch with primitive cat

#define PRIMITIVE_CAT(a, ...) a ## __VA_ARGS__
#define LARGE_LETTER(x) PRIMITIVE_CAT(LARGE_LETTER_, x)

Usage:

char *str = "foo " LARGE_LETTER(A) " baz";

Upvotes: 2

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