Question: When passing a char as a function argument, should I pass the number obtained by calling the string's ord method? #96

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1. kou commented on Oct 17, 2021

   

   kou

   on Oct 17, 2021

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   Yes. Because char is signed 8 bit integer in C.

   But we can pass one byte string directly with the following change:

   diff --git a/ext/fiddle/conversions.c b/ext/fiddle/conversions.c
   index 6e0ce36..f7b0b75 100644
   --- a/ext/fiddle/conversions.c
   +++ b/ext/fiddle/conversions.c
   @@ -209,7 +209,11 @@ rb_fiddle_value_to_generic(int type, VALUE *src, fiddle_generic *dst)
    	dst->pointer = NUM2PTR(rb_Integer(*src));
    	break;
          case TYPE_CHAR:
   -	dst->schar = (signed char)NUM2INT(*src);
   +        if (RB_TYPE_P(*src) == RUBY_T_STRING && RSTRING_LEN(*src) == 1) {
   +            dst->schar = RSTRING_PTR(*src)[0];
   +        } else {
   +            dst->schar = (signed char)NUM2INT(*src);
   +        }
    	break;
          case -TYPE_CHAR:
    	dst->uchar = (unsigned char)NUM2UINT(*src);
2. kojix2 commented on Oct 17, 2021

   

   kojix2

   on Oct 17, 2021

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   Thanks.
   I hadn't thought about changing the Fiddle.
   However, I understand what you are saying. Certainly this is something that many people would do on the Ruby code side .
3. kojix2 commented on Oct 17, 2021

   

   kojix2

   on Oct 17, 2021

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   My issue has been resolved, but as a suggestion for possible changes, shall I leave this issue open?
4. kou commented on Oct 17, 2021

   

   kou

   on Oct 17, 2021

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   Yes, please.
5. kou

   closed this as completedin 2c863efon May 24, 2023
6. matzbot

   added a commit that references this issue on Jun 28, 2023

   [ruby/fiddle] Add support for converting "C" (one character string) t…

   ...

   02661f5
7. MSP-Greg

   added a commit that references this issue on Mar 6, 2024

   Add support for converting "C" (one character string) to char

   ...

   This issue will close once commit 2c863ef is merged into the 'master' branch.

   2c863ef