switch statement matching non-ascii characters
c++, character-encoding
Solution
`á` is a non-ASCII character and is being represented as multiple bytes in either your source code, the `struct dirent`, or both.
If you turn on `-Wmultichar` you will probably get the warning
warning: multi-character character constant
indicating that the character constant `'á'` consists of more than one byte, in which case it's probably in UTF-8, but check (e.g. using `file`). You'll also need to find out the encoding of the `dirent` entries.
In order to match non-ASCII characters in a string you need to:
- make sure that the string and the character are represented in the same encoding, and either
- use a fixed-length encoding (i.e. UCS-4) and a type sufficiently wide to store each codepoint (e.g. `int`), or
- use a restartable variable-length encoding (i.e. UTF-8) and use substring matching.
Look at http://en.cppreference.com/w/cpp/locale/codecvt_utf8 for an example of how to do the conversions.
Problem
I have accented characters in my source code and have tried replacing them with the unicode equivalent. The program compiles and works properly if I use the actual non-ascii character but I'm concerned this may impact portability. When I try using the unicode equivalent I get warning: case label value exceeds maximum value for type or warning: character constant too long for its type and the case is never matched when I run the program. ``` for(int i = 0; i < ent->d_namlen; i++) { switch(ent->d_name[i]) { case 'á' : //0x00E1 ... } } ``` ent is `struct dirent *ent` that gets passed from a calling function. In place of `case 'á' :` I've tried `case '0x00E1' :`, `case L 'u00E1 :`, `case \U000000E9 :` and `case '\u00E1' :` I've tried all without single quotes in which case it won't compile (e.g. says that \u00E1 was not declared in this scope).